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Table of Contents
REVIEW ARTICLE
Year : 2021  |  Volume : 26  |  Issue : 1  |  Page : 17-30

Effects of structured Aerobic Exercise on selected clinical profiles of patients with type 2 diabetes mellitus: A systematic review with meta-analysis


1 LANCET Physiotherapy, Wellness and Research Centre, Enugu, Nigeria
2 Department of Physiotherapy, University of Abuja Teaching Hospital, Abuja, Nigeria
3 Department of Medical Rehabilitation, Faculty of Health Sciences and Technology, College of Medicine, University of Nigeria, Nsukka, Nigeria
4 Department of Health Administration and Management, Faculty of Health Sciences and Technology, College of Medicine, University of Nigeria, Nsukka, Nigeria
5 Department of Medical Laboratory Sciences, College of Medicine, Faculty of Health Sciences and Technology, University of Nigeria, Enugu Campus, Enugu, Nigeria
6 LANCET Physiotherapy, Wellness and Research Centre, Enugu, Nigeria; Department of Medical Rehabilitation, Faculty of Health Sciences and Technology, College of Medicine, University of Nigeria, Nsukka, Nigeria
7 Department of Health Administration and Management, Faculty of Health Sciences and Technology, College of Medicine, University of Nigeria, Nsukka, Nigeria; Department of Nursing Sciences, Faculty of Health Sciences and Technology, College of Medicine, University of Nigeria, Nigeria

Date of Submission01-May-2020
Date of Decision24-Jul-2020
Date of Acceptance07-Sep-2020
Date of Web Publication21-Oct-2020

Correspondence Address:
Echezona Nelson Dominic Ekechukwu
Department of Medical Rehabilitation, Faculty of Health Sciences & Technology, College of Medicine, University of Nigeria, Nigeria; LANCET Physiotherapy, Wellness & Research, Enugu.
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijmh.IJMH_23_20

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  Abstract 

This review sought to examine the pooled effects of Aerobic Exercise (AeroEx) on the glycemic, lipid, cardiovascular, and anthropometric profiles as well as the quality of life (QoL) of patients with type 2 diabetes mellitus (T2DM). Major electronic databases were searched systematically to identify randomized controlled studies that examined the effects of AeroEx in with T2DM. The methodological quality of each study was evaluated using the PEDro scale. Meta-analysis was performed on a given outcome when appropriate. Twelve trials fulfilled the selection criteria. Most of the studies prescribed AeroEx using treadmill (41.7%) or cycle ergometer (58.3%), at a moderate training intensity (58.3%) for ≥3 days/week (100%), 41–60 min/day (66.7%) and for ≥16 weeks (41.6%). Meta-analysis showed a significant effect on glycemic profiles (glycated hemoglobin [SMD = –2.06; CI = –2.34, –1.79], fasting blood glucose [SMD = –1.20; CI = –1.45, –0.95]), lipid profiles (total cholesterol [SMD = –1.35; CI = –1.58, –1.12], low-density lipoprotein [LDL] [SMD = –0.67; CI = –1.22, –0.12]), cardiovascular profiles (maximum oxygen consumption [SMD = 0.58; CI = 0.20, 0.96], diastolic blood pressure [SMD = –0.40; CI = –0.60, –0.21]), anthropometric profiles (percentage body fat [SMD = –1.09; CI = –1.37, –0.82], BMI [SMD = –1.81; CI = –2.16, –0.87]) and QoL (SMD = 2.23; CI = 1.56, 2.90) in favor of AeroEx. In conclusion, chronic AeroEx with moderate intensity induces glycemic control, regulates the lipid profiles, promotes cardiovascular health, and improves overall QoL of patients with T2DM.

Keywords: Aerobic Exercise, clinical profiles, quality of life, systematic review, type-2 diabetes mellitus


How to cite this article:
Ekechukwu NI, Anwara SU, Mgbeojedo UG, Chijioke OU, Onwukwe OS, Ezugwu UA, Ekechukwu EN, Okoronkwo IL. Effects of structured Aerobic Exercise on selected clinical profiles of patients with type 2 diabetes mellitus: A systematic review with meta-analysis. Int J Med Health Dev 2021;26:17-30

How to cite this URL:
Ekechukwu NI, Anwara SU, Mgbeojedo UG, Chijioke OU, Onwukwe OS, Ezugwu UA, Ekechukwu EN, Okoronkwo IL. Effects of structured Aerobic Exercise on selected clinical profiles of patients with type 2 diabetes mellitus: A systematic review with meta-analysis. Int J Med Health Dev [serial online] 2021 [cited 2021 Jan 28];26:17-30. Available from: https://www.ijmhdev.com/text.asp?2021/26/1/17/298779




  Introduction Top


Diabetes mellitus is a general term for the heterogeneous disturbances of metabolism for which the main finding is chronic hyperglycemia caused by impaired insulin secretion and/or impaired insulin action.[1] Type 2 diabetes mellitus (T2DM) is one of the fastest-growing noncommunicable diseases worldwide.[2] The number of people with T2DM (confirmed cases by undertaking diabetes tests) has risen from 108 million in 1980 to 422 million in 2014, while its global prevalence among adults over 18 years of age has risen from 4.7% in 1980 to 8.5% in 2014.[3] The World Health Organization's recommendations for the prevention and management of T2DM include maintaining a healthy weight, consuming a healthy diet, and participation in exercise.[4] Most T2DM prevention programs[5],[6],[7],[8],[9] have recommended Aerobic Exercise with strong evidence supporting this approach. Structured aerobic exercise can help people with T2DM achieve a variety of goals, including increased cardiorespiratory fitness, increased vigor, improved glycemic control, decreased insulin resistance, improved lipid profile, blood pressure reduction, and maintenance of weight loss.[10]

Most systematic reviews and meta-analysis[11],[12],[13],[14] on the effects of aerobic exercise on selected health indices of patients with T2DM appear to have focused on glycemic control with little or no emphasis on other health indices like their quality of life (QoL) and anthropometric indices. The objective of this systematic review was to examine the pooled effects of aerobic exercises on the glycemic, lipid, cardiorespiratory and anthropometric profiles as well as the QoL and wound size of patients with T2DM. We also aimed to develop evidence-based exercise prescription recommendations based on these analyses. We therefore hypothesized that the systematic review of the literature would reveal compelling support for the effectiveness of aerobic exercise in patients with T2DM, such that detailed evidence-based exercise prescription recommendations could be derived.


  Materials and Methods Top


The PICO method[15] was used to define the four major components of the systematic review question: P (patient) = patients with T2DM; I (intervention) = exercise programs that include a substantial aerobic exercise component, with aerobic exercise being defined as ‘a structured exercise program that involves the use of large muscle groups for extended periods of time in activities that are rhythmic in nature, including but not limited to walking, stepping, running, swimming, cycling and rowing;[16] C (comparison) = no intervention or other activities not designed to improve aerobic fitness; and O (outcome) = glycemic, lipid, cardiovascular and athropometric profiles and other health indicators such as QoL and wound size.

The eligibility criteria for article selection were formulated on the basis of the research question. Only randomized controlled trials (RCTs) that investigated the effects of aerobic exercise in patients with T2DM; that the aerobic training protocol was clearly described (e.g., mode, frequency, intensity, and time), and published in English were included. However, study reports published in books, doctoral dissertations, or reports published in conference proceedings were excluded. The primary outcomes of interest were glycemic profiles (glycated hemoglobin and fasting blood glucose [FBG]), total cholesterol, maximum oxygen consumption (VO2max), and percentage body fat and wound size. In addition, other indicators of general health status, particularly those relevant to other lipid (triglycerides [TGs], high-density lipoprotein [HDL], and LDL), cardiorespiratory (systolic and diastolic blood pressures, pulse rate, and respiratory rate), and anthropometric (body weight, body mass index, waist circumference and waist-hip ratio) profiles as well as QoL were also of interest and considered as secondary outcomes in this systematic review.

The following electronic databases were searched online by a research team member: Cochrane Library, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Science Direct, PubMed, and Physiotherapy Evidence Database (PEDro). Google search and a hand search of the reference list of existing articles were also conducted to find papers that did not appear in the main databases. The titles and abstracts of the articles generated by the search strategy were first screened to eliminate irrelevant articles. The articles that met the inclusion criteria after title/abstract screening had their full texts downloaded and reviewed to determine their final eligibility.

The PEDro score of each selected study, which is an indicator of the methodological quality (9–10 = excellent; 6–8 = good; 4–5 = fair; <4 = poor), was identified by searching the PEDro website [Table 1]. Based on the PEDro assessment and sample size used, the level of evidence was assigned to each study. High-quality RCTs (rated as good or excellent by PEDro and sample size >50) were considered level 1 evidence, whereas lower-quality RCTs were considered level 2 evidence (rated as fair or poor by PEDro, or sample size ≤50). The article selection and data extraction were performed by two research team members independently. The results were then confirmed by the principal investigator. Meta-analysis was conducted when appropriate to estimate the pooled treatment effect using Review Manager (version 5.1, the Nordic Cochrane Center, Copenhagen, Denmark). Meta-analysis was performed only if three or more studies measured the same outcome of interest. The change scores (postintervention score–preintervention score) for each of the experimental and control groups were used for the meta-analysis.
Table 1: Summary of methodological quality of studies and diabetes characteristic

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  Results Top


A PRISMA flow diagram of the literature search and selection is presented in [Figure 1]. From 4547 potentially relevant studies retrieved from our main and additional manual search, we identified 12 trials that fulfilled the inclusion criteria. Considering both the PEDro ratings and sample size used, seven studies provided level 1 evidence whereas others were considered as level 2 studies. The methodological quality of the included trials ranged from fair to good, with an average PEDro score of 7.8. Eleven trials were methodologically good quality trials with scores ≥ 6, seven trials had a sample size ≥ 50 as shown in [Table 1].
Figure 1: PRISMA diagram

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In most of the selected studies aerobic exercise was performed using treadmill (41.7%) or cycle ergometer (58.3%), at a moderate training intensity of 61%–76% HRmax (58.3%) for 3–5 days per week (100%), 41–60 min per day (66.7%) and for ≥16 weeks (41.6%) as shown in [Table 2]. Of the 18 outcome variables measured, four (waist–hip ratio, respiratory rate, pulse rate, and wound size) were not included in the meta-analysis because they were assessed in less than three studies. One of these outcomes (wound size) is a primary outcome while the rest are secondary outcomes. Of the remaining outcomes measured, glycated hemoglobin (HbA1c) and FBGwere the most frequently measured outcomes (9 and 10 studies, respectively) among the studies involved in the meta-analysis.
Table 2: Summary aerobic exercise protocols

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  Effects of Aerobic Exercise on the Primary Outcomes Top


Glycated Hemoglobin

The meta-analysis incorporated nine trials[17],[18],[19],[20],[21],[22],[23],[24],[25] that assessed glycated hemoglobin resulting in a total of 611 participants. There was a significant pooled effect (reduction) on HbA1c in favor of the aerobic exercise group (SMD = –2.06; CI = –2.34, –1.79) as shown in [Figure 2]A. When all level 2 studies were extruded, only four studies[17],[19],[21],[22] with level 1 evidence (contributing 483 participants) were left. The meta-analysis of these studies still revealed that aerobic exercise had a significant pooled effect in decreasing HbA1c (SMD = –1.93; CI = –2.23, –1.63) as shown in [Figure 2]B.
Figure 2: A: Forest plot for glycated hemoglobin (HbA1c). B: Forest plot for glycated hemoglobin (HbA1c) using only Level 1 trials

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Total cholesterol

Six trials[17],[20],[22],[26],[27],[28] measured total cholesterol that gave a total of 724 participants. A study[22] had a significant effect in reducing TC that favored the control group while the rest of the trials had significant effects in favor of the aerobic exercise group. Summarily, the pooled decreasing effect (SMD = –1.35; CI = –1.58, –1.12) was in favor of aerobic exercise as shown in [Figure 3]A. Also, when the only level 2 study[20] was extruded (leaving a total of 686 participants involved in the analysis), the pooled decreasing effect was still in favor of the aerobic exercise group (SMD = –1.28; CI = –1.51, –1.05) as shown in [Figure 3]B.
Figure 3: (A) Forest plot for total cholesterol (TC). (B) Forest plot for total cholesterol (TC) using only Level 1 trials

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Fasting blood glucose

FBG was measured in 10 of the included trials[19],[20],[21],[22],[23],[24],[25],[26],[27],[28] resulting in a total of 720 participants; seven of them had significant decreasing effects in favor of the aerobic exercise while three of the trials[19],[22],[23] had no significant effect. However, the pooled decreasing effect on FBG (SMD = –1.20; CI = –1.45, –0.95) was significantly in favor of the aerobic exercise group as shown in [Figure 4]A. In the same vein, a significant decreasing effect in favor of aerobic exercise was also found in the analysis involving only level 1 studies with a total of 607 participants (SMD = –1.70; CI = –1.33, –0.80) as shown in [Figure 4]B.
Figure 4: (A) Forest plot for fasting blood glucose (FBG). (B) Forest plot for fasting blood glucose (FBG) using only Level 1 trials

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Maximum oxygen consumption (VO2max)

Four trials[21],[22],[24],[25] with a total of 197 participants measured this primary outcome. One of the studies[22] had a significant increasing effect in favor of the control group; another study[24] had no significant effect, while the other two trials[21],[25] had significant improving effects in favor of the aerobic exercise group. The pooled improving effect on VO2max (SMD = 0.58; CI = 0.20, 0.96) was significantly in favor of the aerobic exercise group as shown in [Figure 5]A. However, the analysis using the two trials[21],[22] with level 1 evidence that gave a total of 140 participants showed no significant benefit (SMD = 0.06; CI = –0.40, –0.51) as shown in [Figure 5]B.
Figure 5: (A) Forest plot for maximal oxygen consumption (VO2max). (B) Forest plot for maximal oxygen consumption (VO2max) using only Level 1 trials

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Percentage body fat

Three trials, all with level 1 evidence[17],[21],[22] that resulted in a total of 391 participants measured percentage body fat. One of the trials[17] had a significant decreasing effect in favor of the aerobic exercise group; another study[22] had a significant decreasing effect in favor of the control group, while the other trial showed no significant effect. However, the pooled effect showed a significant reduction of %BF (SMD = –1.09; CI = –1.37, –0.82) in favor of aerobic exercise as shown in [Figure 6].
Figure 6: Forest plot for percentage body fat (%BF)

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  Effects of Aerobic Exercise on the Secondary Outcomes Top


Blood pressure

Systolic and diastolic blood pressures were measured in six trials[17],[19],[21],[22],[25],[27] that gave a total of 597 participants for each of the outcomes. For the systolic blood pressure, three trials[21],[25],[27] had significant decreasing effects in favor of the aerobic exercise group, a study[22] had a significant decreasing effect in favor of the control group while two trials[17],[19] showed no significant effect. The pooled effect (SMD = –0.19, CI = –0.40, 0.02) was however nonsignificant as shown in [Figure 7]. On the contrary, there was a significant decreasing pooled effect on diastolic blood pressure (SMD = –0.40; CI = –0.60, –0.21) in favor of the aerobic exercise group as shown in [Figure 8].
Figure 7: Forest plot for systolic blood pressure (SBP)

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Figure 8: Forest plot for diastolic blood pressure (DBP)

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High-density lipoprotein

Four trials[17],[22],[23],[26] with a total of 560 participants assessed the effect of aerobic exercise on HDL. Three of the trials[17],[23],[26] had a nonsignificant increasing effect in favor of the aerobic exercise group while the fourth trial[22] had a significant increasing effect on HDL. The pooled effect (SMD = 0.18; CI = –0.02, 0.37) in improving HDL for these four trials was in favor of the aerobic exercise group though nonsignificantly as shown in [Figure 9].
Figure 9: Forest plot for high-density lipoprotein (HDL)

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Low-density lipoprotein

Four trials[17],[22],[23],[26] with a total of 560 participants assessed the effect of aerobic exercise on LDL. Three of the trials[17],[22],[26] had a significant decreasing effect in favor of the aerobic exercise group while a trial[23] had a significant decreasing effect in favor of the control group. However, the overall decreasing effect (SMD = –0.67; CI = –1.22, –0.12) was significantly in favor of aerobic exercise as shown in [Figure 10].
Figure 10: Forest plot for low-density lipoprotein (LDL)

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Triglyceride

Four out of the six trials (752 participants) that assessed TG[17],[19],[20],[26] had significant decreasing effects in favor of the aerobic exercise group while the other two studies[21],[22] showed no significant effect on TG. There was, however, a significant decreasing pooled effect on TG (SMD = –.1.15; CI = –1.43, –0.8) in favor of aerobic exercise as shown in [Figure 11].
Figure 11: Forest plot for triglycerides (TG)

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Body weight

Two of the three trials (352 participants) that assessed the effects of aerobic exercise on the body weight of patients with T2DM[17],[25] reported a significant decreasing effect in favor of the aerobic exercise group while a trial[22] showed a significant decreasing effect in favor of the control group. However, the pooled effect (SMD = –1.15; CI = –1.43, –0.87) was significantly in favor of aerobic exercise as shown in [Figure 12].
Figure 12: Forest plot for body weight (BW)

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Body mass index

A total of seven studies[17],[18],[19],[21],[22],[23],[25] with a total of 555 participants incorporated Body mass index as an outcome. Three of these trials[17],[18],[19] had a significant decreasing effect in favor of the aerobic exercise group; two trials[21],[24] had no significant effect while the other two trials[22],[25] showed significant decreasing effects in favor of the control group. However, the pooled effect (SMD = –1.81; CI = –2.16, –0.87) was significantly in favor of aerobic exercise as shown in [Figure 13].
Figure 13: Forest plot for body mass index (BMI)

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Waist circumference

Waist circumference was measured as an outcome in three trials[17],[22],[25] that resulted in 352 participants. Two of these trials[17],[22] showed a significant decreasing effect in favor of aerobic exercise while the other study[25] had a significant decreasing effect in favor of the control group. However, the pooled effect (SMD = –2.72; CI = –3.49, –1.94) was significantly in favor of aerobic exercise as shown in [Figure 14].
Figure 14: Forest plot for waist circumference (WC)

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Quality of life

This outcome was assessed in three trials[20],[23],[24] that gave a total of 72 participants. Two of the trials[20],[23] had a significant increasing effect in favor of the aerobic exercise group while the other trial[24] showed no significant effect on QOL. However, there was an increasing significant pooled effects on QoL (SMD = 2.23; CI = 1.56, 2.90) in favor of the aerobic exercise group as shown in [Figure 15].
Figure 15: Forest plot for quality of life (QoL)

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  Discussion Top


This study provides an updated review of the current evidence related to the use of aerobic exercise in influencing various health indicators in persons living with T2DM, and provides the foundation for developing an evidence-based exercise prescription for this population. Majority of the studies reviewed prescribed aerobic exercise using treadmill or cycle ergometer at moderate training intensity for 16 weeks and above, 3–5 days per week and 41–60 min per day. Treadmill and cycle ergometers are commonly found aerobic training devices in most labs/gymnasia possibly because structured aerobic exercise parameters such as time, intensity using heart rates, distance covered for estimating VO2max, calories burnt, etc., can be objectively assessed electronically using these modes as compared to other modes such as stair-climbing, brisk walking, yoga, etc. Also, these modes do not require large space when compared to modes such as walking and running utilized in 6-min walk tests and the 1.5 miles run tests, respectively. Therefore, structured aerobic exercise can be objectively prescribed for with T2DM using a threadmill and/or cycle ergometers.

Glycated hemoglobin’s are characteristically Ketoamines, formed through a two-step nonenzymatic pathway between hemoglobin and blood glucose.[29] Blood glucose and hemoglobin are combined to form aldimine as a first step, which is a reversible form. In the second step, this labile aldimine is slowly converted to ketoamine form which is stable and irreversible.[30] In individuals with poorly controlled diabetes, the quantities of these glycated hemoglobin’s are much higher than in healthy people. The HbA1c level is directly proportional to average blood glucose concentration over the previous 4 weeks to 3 months or the average lifespan of the erythrocyte.[30] Higher amounts of HbA1c in diabetic patients, indicating poorer control of blood glucose levels, have been associated with diabetic complications such as cardiovascular disease, nephropathy, and retinopathy.[31] Studies[32],[33],[34],[35] have shown that HbA1c is an important indicator of glycemic control.

In this review, aerobic exercise was significantly effective in reducing HbA1c in patients with T2DM. Of the nine included studies that assessed HbA1c, only the study by Bello et al.,[23] had no significant effect in reducing HbA1c among their participants; although, the pooled effects of the nine studies was in favor of aerobic exercise (having a significant decreasing effects on HbA1c). Aerobic exercise improves glycemic control in type 2 diabetes through several mechanisms. During exercise, glucose uptake occurs in an exercise intensity/duration-dependent manner due to increased glucose delivery, glucose transport, and glucose metabolism.[36],[37] Also, post-exercise enhancement of insulin sensitivity is a contributory mechanism for explaining exercise-induced glycemic control. Other mechanisms include Redox homeostasis; exercise-induced oxidative stress, stress-activated protein kinase (SAPK) signaling, and mitogen-activated protein kinase (MAPK) signaling.[37]

Of the six studies that incorporated total cholesterol in this meta-analysis, only one[22] reported nonsignificant effect of aerobic exercise. However, the pooled effects of the six RCTs were significantly in favor of aerobic exercise. Therefore, one can substantially state that aerobic exercise plays a vital role in the control and management of the total cholesterol of patients with T2DM. The most commonly used measure of cholesterol is arguably total cholesterol, a measure that includes LDL cholesterol and HDL cholesterol.[38] A reduction in total cholesterol is considered the gold standard in preventative cardiovascular medicine.[38] This result highlights the importance aerobic exercise in reducing serum cholesterol levels among diabetic patients. While the mechanisms underlying the effect of aerobic exercise on the lipid profile are unclear, aerobic exercise appears to enhance the ability of skeletal muscles to utilize lipids, thus reducing plasma lipid levels.[39] The mechanisms may also include increases in lecithin cholesterol acyltransferase (LCAT)—the enzyme responsible for ester transfer to HDL cholesterol,[40] which has been found to increase following exercise training.[41] Also, exercise-induced increase in lipoprotein lipase activity[42] is another possible mechanism for regulating total cholesterol level in with T2DM using aerobic exercise.

Fasting blood glucose is the most common method for diagnosing diabetes and monitoring of blood glucose among diabetic patients because it is easy, convenient and less expensive.[43] In this review, aerobic exercise had a significant pooled effect in decreasing the fasting blood glucose level of patients with T2DM. All the ten studies involved in this meta-analysis showed significant effect of aerobic exercise on the blood glucose level. Dysregulation of insulin activity (insulin resistance) and secretion (insulin deficiency) occurs in the development of diabetes. Aerobic exercise can circumvent dysfunctional insulin signaling and offers a potent nonpharmacological tool to augment glucose uptake in insulin-resistant muscle to normalize glycemic control[44] through three mechanisms. First by increasing muscle capillarization that enhances glucose delivery. Secondly, by increasing Glucose Transporter type 4 (GLUT4) expression and translocation that enhance glucose transport. Finally by improving hexokinase and mitochondrial expression that enhances glucose metabolism.[44]

The meta-analysis for VO2max showed that the pooled effect in increasing VO2max was in favor of the aerobic exercise group. This implies that aerobic exercise was significantly more effective in improving VO2max among with T2DM. It has been established that patients with T2DM even in the absence of clinically apparent cardiovascular complications have reduced cardiorespiratory endurance as measured by VO2max.[45] Studies have fingered impairment in glycemic control,[46] insulin resistance,[47],[48] endothelial dysfunction,[49] decreased blood flow,[50] abnormal tissue hemoglobin oxygen saturation, diastolic dysfunction and decreased cardiac perfusion[51] and more recently decreased muscle mitochondrial function[52] to be partly responsible for the limitations in VO2max among patients with T2DM. These factors (impaired glycemic control, insulin resistance, endothelial dysfunction etc.) can be reversed with the use of aerobic exercise. Therefore these factors may explain the mechanism by which aerobic exercise improves VO2max among patients with T2DM. It is however pertinent that this result be interpreted with caution because similar meta-analysis with only high quality (level 1) studies[22],[25] showed no significant effect. This may have been due to the small sample size drawn from the two RCTs (140 subjects). Therefore, more high quality randomized clinical trials assessing the effects of aerobic exercise on the VO2max of with T2DM is recommended.

The pooled effect in reducing percentage body fat was significantly in favor of aerobic exercise. The major complication of diabetes is cardiovascular disorders which can be further complicated by poor body composition indices such as percentage body fat. It has been demonstrated that loss of body fat leads to a reduction in insulin resistance. The Possible mechanisms underlying the aerobic exercise-induced fat loss effect include increased exercise and post-exercise fat oxidation,[53] decreased post-exercise appetite[54] and exercise-induced browning of adipose tissues.[55] Skeletal muscle perilipin 3(PLIN3) and coatomer proteins (GBF1, ARF1, Sec23a, and ARFRP1) have been found to increase following aerobic exercise and these are associated with fat oxidation.[56] Appetite hormones such as ghrelin, peptide tyrosine (PYY), and glucagon-like peptide 1 (GLP-1) are well known to play a critical role in nutrient signaling and subsequently in controlling appetite.[57] Aerobic exercise has been found to modulate these hormones such that appetite becomes suppressed.[58],[59] Also, aerobic exercise-induced anorexia has also been explained via its increasing effect on interleukin 6.[54]

There was a significant decrease in DBP and a nonsignificant decrease in SBP in favor of aerobic exercise. This implies that aerobic exercise is capable to reducing blood pressure especially the DSP among T2DM patients. This is achieved by strengthening the cardiac muscles, improving the efficiency of cardiac contractility and the resultant decrease in forceful ejection of blood from the heart.[60] Aerobic exercise regulates blood pressure in patients with T2DM through its effects on the endothelia tissues and peripheral resistance,[61] vessel elasticity[62] as well as blood volume and cardiac output.[63] In the same vein, aerobic exercise was effective in decreasing body weight, body mass index, and waist circumference. This was possibly achieved through the aerobic exercise-induced reduction in body fat as discussed above.

LDL and TG were significantly decreased with the pooled effects in favor of aerobic exercise while HDL was increased in favor of the aerobic exercise group though nonsignificantly. This implies that while aerobic exercise was effective in reducing LDL and TG, it may be effective in increasing HDL. Dyslipidemia is associated with T2DM and the most common patterns of dyslipidemia in diabetic patients are decreased HDL and elevated LDL and TGs.[64] Aerobic exercise training increases the level of HDL especially the HDL-2 subfraction mainly by inhibiting HDL catabolism[65] and/or in few cases increasing HDL synthesis.[38] Also exercise-induced increase in lipoprotein lipase (LPL)[66] results in hydrolysis of TG-rich lipoproteins and this partly explains the decrease in TG and LDL following exercise training.

Finally, the increase in QoL was significantly in favor of the aerobic exercise group. This implies that aerobic exercise was significantly effective in improving the overall QoL of persons with T2DM. T2DM has an adverse effect on QoL. Most patients suffer from a variety of long-term complications such as neuropathy, nephrolopathy, retinopathy, myocardial infarction, angina pectoris, stroke, and amputation.[67] In addition, the trouble of taking oral antidiabetic agents several times a day, the fear of subcutaneous injection of insulin, and incidents of hypoglycemia might depress diabetic patients and further reduce health-related quality of life (HRQoL).[67] Studies[68],[69] have shown that the HRQoL of diabetic patients is worse than that of similarly aged nondiabetics. It is possible that the effects of aerobic exercise in inducing optimal cardiovascular health, glycemic control, regulation of lipid and anthropometric profiles of patients with T2DM may be responsible for the improved overall quality of health after chronic aerobic exercise.


  Conclusion Top


Aerobic exercise using treadmill and/or cycle ergometer at moderate training intensity for at least 16 weeks, not less than 3 days per week and for about 40 min per day is capable of inducing glycemic control, regulate the lipid profiles, promote cardiovascular health, and improve overall QoL of patients with T2DM.

Financial support and sponsorship

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Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Kerner W, Brückel J; German Diabetes Association. Definition, classification and diagnosis of diabetes mellitus. Exp Clin Endocrinol Diabetes 2014;122:384-6.  Back to cited text no. 1
    
2.
Buowari OY Diabetes mellitus in developing countries and case series. In Diabetes mellitus-insights and perspectives. Manchester: InTech; 2013.  Back to cited text no. 2
    
3.
World Health Organization. World health statistics 2016: Monitoring health for the SDGs sustainable development goals. Geneva: World Health Organization; 2016.  Back to cited text no. 3
    
4.
World Health Organization. Media centre – fact sheets on diabetes. Updated November, 2017. Available from: http://www.who.int/mediacentre/factsheets/fs312/en/. [Last accessed on 2017 Dec 9 at 16:47 hrs GMT].  Back to cited text no. 4
    
5.
Fox CS, Golden SH, Anderson C, Bray GA, Burke LE, de Boer IH, et al; American Heart Association Diabetes Committee of the Council on Lifestyle and Cardiometabolic Health, Council on Clinical Cardiology, Council on Cardiovascular and Stroke Nursing, Council on Cardiovascular Surgery and Anesthesia, Council on Quality of Care and Outcomes Research, and the American Diabetes Association. Update on prevention of cardiovascular disease in adults with type 2 diabetes mellitus in light of recent evidence: A scientific statement from the American heart association and the American Diabetes Association. Circulation 2015;132:691-718.  Back to cited text no. 5
    
6.
American Diabetes Association. Standards of medical care in diabetes—2016 abridged for primary care providers. Clin Diabetes 2016;34:3.  Back to cited text no. 6
    
7.
Karstoft K, Pedersen BK Exercise and type 2 diabetes: Focus on metabolism and inflammation. Immunol Cell Biol 2016;94:146-50.  Back to cited text no. 7
    
8.
Sacks J The essential role of exercise in the management of type 2 diabetes. Cleveland Clin J Med 2017;84:S15.  Back to cited text no. 8
    
9.
American Diabetes Association. 4. Lifestyle management: Standards of medical care in diabetes—2018. Diabetes Care 2018;41:S38-50.  Back to cited text no. 9
    
10.
Colberg SR, Sigal RJ, Fernhall B, Regensteiner JG, Blissmer BJ, Rubin RR, et al; American College of Sports Medicine; American Diabetes Association. Exercise and type 2 diabetes: The American college of sports medicine and the American Diabetes Association: Joint position statement. Diabetes Care 2010;33:e147-67.  Back to cited text no. 10
    
11.
Jelleyman C, Yates T, O’Donovan G, Gray LJ, King JA, Khunti K, et al. The effects of high-intensity interval training on glucose regulation and insulin resistance: A meta-analysis. Obesity Rev 2015;16:942-61.  Back to cited text no. 11
    
12.
Liubaoerjijin Y, Terada T, Fletcher K, Boulé NG Effect of aerobic exercise intensity on glycemic control in type 2 diabetes: A meta-analysis of head-to-head randomized trials. Acta Diabetol 2016;53:769-81.  Back to cited text no. 12
    
13.
Way KL, Hackett DA, Baker MK, Johnson NA The effect of regular exercise on insulin sensitivity in type 2 diabetes mellitus: A systematic review and meta-analysis. Diabetes Metab J 2016;40:253-71.  Back to cited text no. 13
    
14.
Grace A, Chan E, Giallauria F, Graham PL, Smart NA Clinical outcomes and glycaemic responses to different aerobic exercise training intensities in type II diabetes: A systematic review and meta-analysis. Cardiovasc Diabetol 2017;16:37.  Back to cited text no. 14
    
15.
Oxford: Centre for Evidence-Based Medicine; 2017. Available from: http://www. cebm.net/. [Last accessed on 2020 Apr 15].  Back to cited text no. 15
    
16.
Farooqui AA, Farooqui T Diet and exercise in cognitive function and neurological diseases. Hoboken, NJ: John Wiley & Sons; 2015.  Back to cited text no. 16
    
17.
Sigal RJ, Kenny GP, Boulé NG, Wells GA, Prud’homme D, Fortier M, et al. Effects of aerobic training, resistance training, or both on glycemic control in type 2 diabetes: A randomized trial. Ann Intern Med 2007;147:357-69.  Back to cited text no. 17
    
18.
Marcus RL, Smith S, Morrell G, Addison O, Dibble LE, Wahoff-Stice D, et al. Comparison of combined aerobic and high-force eccentric resistance exercise with aerobic exercise only for people with type 2 diabetes mellitus. Phys Ther 2008;88:1345-54.  Back to cited text no. 18
    
19.
Praet SF, van Rooij ES, Wijtvliet A, Boonman-de Winter LJ, Enneking T, Kuipers H, et al. Brisk walking compared with an individualised medical fitness programme for patients with type 2 diabetes: A randomised controlled trial. Diabetologia 2008;51:736-46.  Back to cited text no. 19
    
20.
Aylin K, Arzu D, Sabri S, Handan TE, Ridvan A The effect of combined resistance and home-based walking exercise in type 2 diabetes patients. Int J Diabetes Dev Ctries 2009;29:159-65.  Back to cited text no. 20
    
21.
Yavari A, Hajiyev AM, Naghizadeh F The effect of aerobic exercise on glycosylated hemoglobin values in type 2 diabetes patients. J Sports Med Phys Fitness 2010;50:501-5.  Back to cited text no. 21
    
22.
Ng CL, Goh SY, Malhotra R, Østbye T, Tai ES Minimal difference between aerobic and progressive resistance exercise on metabolic profile and fitness in older adults with diabetes mellitus: A randomised trial. J Physiother 2010;56:163-70.  Back to cited text no. 22
    
23.
Bello AI, Owusu-Boakye E, Adegoke BO, Adjei DN Effects of aerobic exercise on selected physiological parameters and quality of life in patients with type 2 diabetes mellitus. Int J Gen Med 2011;4:723-7.  Back to cited text no. 23
    
24.
D’hooge R, Hellinckx T, Van Laethem C, Stegen S, De Schepper J, Van Aken S, et al. Influence of combined aerobic and resistance training on metabolic control, cardiovascular fitness and quality of life in adolescents with type 1 diabetes: A randomized controlled trial. Clin Rehabil 2011;25:349-59.  Back to cited text no. 24
    
25.
Yan H, Prista A, Ranadive SM, Damasceno A, Caupers P, Kanaley JA, et al. Effect of aerobic training on glucose control and blood pressure in T2DDM east african males. ISRN Endocrinol 2014;2014:864897.  Back to cited text no. 25
    
26.
Gordon LA, Morrison EY, McGrowder DA, Young R, Fraser YT, Zamora EM, et al. Effect of exercise therapy on lipid profile and oxidative stress indicators in patients with type 2 diabetes. BMC Complement Altern Med 2008;8:21.  Back to cited text no. 26
    
27.
Tiwari S, Gehlot S, Tiwari SK, Singh G Effect of walking (aerobic isotonic exercise) on physiological variants with special reference to prameha (diabetes mellitus) as per prakriti. Ayu 2012;33:44-9.  Back to cited text no. 27
    
28.
Nwankwo MJ, Okoye GC, Victor EA, Obinna EA Effect of twelve weeks supervised aerobic exercise on ulcer healing and changes in selected biochemical profiles of diabetic foot ulcer subjects. Int J Diabetes Res 2014;3:41-8.  Back to cited text no. 28
    
29.
d’Emden MC, Shaw JE, Jones GR, Cheung NW Guidance concerning the use of glycated haemoglobin (hba1c) for the diagnosis of diabetes mellitus. Med J Aust 2015;203:89-90.  Back to cited text no. 29
    
30.
Haque KS, Siddiqui MR Clinical significance of glycated hemoglobin (HbA1c). Anwer Khan Mod Med College J 2013;4:3-5.  Back to cited text no. 30
    
31.
Parry HM, Deshmukh H, Levin D, Van Zuydam N, Elder DH, Morris AD, et al. Both high and low HbA1c predict incident heart failure in type 2 diabetes mellitusCLINICAL PERSPECTIVE. Circ Heart Fail 2015;8:236-42.  Back to cited text no. 31
    
32.
Kohnert KD, Heinke P, Vogt L, Salzsieder E Utility of different glycemic control metrics for optimizing management of diabetes. World J Diabetes 2015;6:17-29.  Back to cited text no. 32
    
33.
Hashimoto K, Koga M Indicators of glycemic control in patients with gestational diabetes mellitus and pregnant women with diabetes mellitus. World J Diabetes 2015;6:1045-56.  Back to cited text no. 33
    
34.
Suh S, Kim JH Glycemic variability: How do we measure it and why is it important? Diabetes Metab J 2015;39:273-82.  Back to cited text no. 34
    
35.
Wan EYF, Fung CSC, Wong CKH, Chin WY, Lam CLK Association of hemoglobin A1C levels with cardiovascular disease and mortality in Chinese patients with diabetes. J Am Coll Cardiol 2016;67:456-8.  Back to cited text no. 35
    
36.
Richter EA, Hargreaves M Exercise, GLUT4, and skeletal muscle glucose uptake. Physiol Rev 2013;93:993-1017.  Back to cited text no. 36
    
37.
Parker L, Shaw CS, Stepto NK, Levinger I Exercise and glycemic control: Focus on redox homeostasis and redox-sensitive protein signaling. Front Endocrinol (Lausanne) 2017;8:87.  Back to cited text no. 37
    
38.
Mann S, Beedie C, Jimenez A Differential effects of aerobic exercise, resistance training and combined exercise modalities on cholesterol and the lipid profile: Review, synthesis and recommendations. Sports Med 2014;44:211-21.  Back to cited text no. 38
    
39.
McClelland GB, Lyons SA, Robertson CE Fuel use in mammals: Conserved patterns and evolved strategies for aerobic locomotion and thermogenesis. Integr Comp Biol 2017;57:231-9.  Back to cited text no. 39
    
40.
Zakiev E, Feng M, Sukhorukov V, Kontush A HDL-targeting therapeutics: Past, present and future. Curr Pharm Des 2017;23:1207-15.  Back to cited text no. 40
    
41.
Kieffer AJ, Walzem RL Modulation of lipids, lipoproteins, and other biomarkers with egg consumption and exercise. In: Watson RR, De Meester F, editors. Handbook of eggs in human function. Wageningen: Wageningen Academic Publishers; 2015. pp. 676-82.  Back to cited text no. 41
    
42.
Griffiths K, Pazderska A, Ahmed M, McGowan A, Maxwell AP, McEneny J, et al. Type 2 diabetes in young females results in increased serum amyloid A and changes to features of high density lipoproteins in both HDL2 and HDL3. J Diabetes Res 2017;2017:1314864.  Back to cited text no. 42
    
43.
American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care 2010;33:S62.  Back to cited text no. 43
    
44.
Sylow L, Kleinert M, Richter EA, Jensen TE Exercise-stimulated glucose uptake—regulation and implications for glycaemic control. Nat Rev Endocrinol 2017;13:133.  Back to cited text no. 44
    
45.
Reusch JE, Bridenstine M, Regensteiner JG Type 2 diabetes mellitus and exercise impairment. Rev Endocr Metab Disord 2013;14:77-86.  Back to cited text no. 45
    
46.
Wilkerson DP, Poole DC, Jones AM, Fulford J, Mawson DM, Ball CI, et al. Older type 2 diabetic males do not exhibit abnormal pulmonary oxygen uptake and muscle oxygen utilization dynamics during submaximal cycling exercise. Am J Physiol Regul Integr Comp Physiol 2011;300:R685-92.  Back to cited text no. 46
    
47.
Chen CN, Chuang LM, Wu YT Clinical measures of physical fitness predict insulin resistance in people at risk for diabetes. Phys Ther 2008;88:1355-64.  Back to cited text no. 47
    
48.
Jun EH, Choi BY, Lee DC, Lee JW, Lee JY Cardiopulmonary fitness is independently associated with insulin resistance in non-diabetes mellitus patients of a university hospital in Korea. Korean J Fam Med 2013;34:139-44.  Back to cited text no. 48
    
49.
Alduhishy A Cardiorespiratory fitness: A strong predictor of insulin resistance among high-risk patients developing type 2 diabetes (T2D). Physiotherapy 2015;101:e50.  Back to cited text no. 49
    
50.
Jansen JF, van Bussel FC, van de Haar HJ, van Osch MJ, Hofman PA, van Boxtel MP, et al. Cerebral blood flow, blood supply, and cognition in type 2 diabetes mellitus. Sci Rep 2016;6:10.  Back to cited text no. 50
    
51.
Zafrir B, Azaiza M, Gaspar T, Dobrecky-Mery I, Azencot M, Lewis BS, et al. Low cardiorespiratory fitness and coronary artery calcification: Complementary cardiovascular risk predictors in asymptomatic type 2 diabetics. Atherosclerosis 2015;241:634-40.  Back to cited text no. 51
    
52.
Menshikova EV, Ritov VB, Dube JJ, Amati F, Stefanovic-Racic M, Toledo FGS, et al. Calorie restriction-induced weight loss and exercise have differential effects on skeletal muscle mitochondria despite similar effects on insulin sensitivity. J Gerontol A Biol Sci Med Sci 2017;73:81-7.  Back to cited text no. 52
    
53.
Boutcher SH High-intensity intermittent exercise and fat loss. J Obes 2011;2011:868305.  Back to cited text no. 53
    
54.
Hunschede S, Kubant R, Akilen R, Thomas S, Anderson GH Decreased appetite after high-intensity exercise correlates with increased plasma interleukin-6 in normal-weight and overweight/obese boys. Curr Dev Nutr 2017;1:e000398.  Back to cited text no. 54
    
55.
Aldiss P, Betts J, Sale C, Pope M, Budge H, Symonds ME Exercise-induced ‘browning’of adipose tissues. Metabolism-Clinical and Experimental. 2018;81:63-70.  Back to cited text no. 55
    
56.
Covington JD, Galgani JE, Moro C, LaGrange JM, Zhang Z, Rustan AC, et al. Skeletal muscle perilipin 3 and coatomer proteins are increased following exercise and are associated with fat oxidation. PLoS One 2014;9:e91675.  Back to cited text no. 56
    
57.
Ahima RS, Antwi DA Brain regulation of appetite and satiety. Endocrinol Metab Clin North Am 2008;37:811-23.  Back to cited text no. 57
    
58.
Deighton K, Barry R, Connon CE, Stensel DJ Appetite, gut hormone and energy intake responses to low volume sprint interval and traditional endurance exercise. Eur J Appl Physiol 2013;113:1147-56.  Back to cited text no. 58
    
59.
Schubert MM, Sabapathy S, Leveritt M, Desbrow B Acute exercise and hormones related to appetite regulation: A meta-analysis. Sports Med 2014;44:387-403.  Back to cited text no. 59
    
60.
MacDougall D, MacDougall JD, Sale D The physiology of training for high performance. Oxford: Oxford University Press; 2014.  Back to cited text no. 60
    
61.
Phillips SA, Mahmoud AM, Brown MD, Haus JM Exercise interventions and peripheral arterial function: Implications for cardio-metabolic disease. Prog Cardiovasc Dis 2015;57:521-34.  Back to cited text no. 61
    
62.
Brozic AP, Marzolini S, Goodman JM Effects of an adapted cardiac rehabilitation programme on arterial stiffness in patients with type 2 diabetes without cardiac disease diagnosis. Diab Vasc Dis Res 2017;14:104-12.  Back to cited text no. 62
    
63.
Kim YS, Seifert T, Brassard P, Rasmussen P, Vaag A, Nielsen HB, et al. Impaired cerebral blood flow and oxygenation during exercise in type 2 diabetic patients. Physiol Rep 2015;3:e12430.  Back to cited text no. 63
    
64.
Qi Q, Liang L, Doria A, Hu FB, Qi L Genetic predisposition to dyslipidemia and type 2 diabetes risk in two prospective cohorts. Diabetes 2012;61:745-52.  Back to cited text no. 64
    
65.
Ramadevi K, Kumar BV Response of exercise training on high density lipoprotein-cholesterol and its subfractions. Univ J Pre Paraclin Sci2015;1:1-10.  Back to cited text no. 65
    
66.
Sasaki T, Nakata R, Inoue H, Shimizu M, Inoue J, Sato R Role of AMPK and pparγ1 in exercise-induced lipoprotein lipase in skeletal muscle. Am J Physiol Endocrinol Metab 2014;306:E1085-92.  Back to cited text no. 66
    
67.
Lu Y, Wang N, Chen Y, Nie X, Li Q, Han B, et al. Health-related quality of life in type-2 diabetes patients: A cross-sectional study in east China. BMC Endocr Disord 2017;17:38.  Back to cited text no. 67
    
68.
Grandy S, Fox KM EQ-5D visual analog scale and utility index values in individuals with diabetes and at risk for diabetes: Findings from the study to help improve early evaluation and management of risk factors leading to diabetes (SHIELD). Health Qual Life Outcomes 2008;6:18.  Back to cited text no. 68
    
69.
Hourani EM, Hammad SM, Shaheen A, Amre HM Health-related quality of life among Jordanian adolescents. Clin Nurs Res 2017;26:337-53.  Back to cited text no. 69
    


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