Exercise Improves Glycemic Control, Body Composition and Aerobic Capacity in Obese Diabetics, Systematic Review Finds

A systematic review of nine randomized controlled trials has concluded that exercise training produces measurable benefits across a broad range of physical and physiological functions in people who live with both obesity and diabetes. The review, published in the Bulletin of Faculty of Physical Therapy, synthesized evidence from 383 individuals with diabetes mellitus and obesity, and found that both aerobic and resistance training improved glycemic control, while specific exercise modalities showed distinct advantages for body composition, muscular strength, inflammatory markers and aerobic capacity. The average methodological quality of the included trials, scored on the Physiotherapy Evidence Database scale, was 6.4 out of a possible 10, a level the authors describe as reflecting good quality.

The research team, led by Deepika Singla and Tasneem Zafar with co-author Shaif Khan, conducted a literature search across PubMed, ERIC and PEDro databases covering publications from 2000 to January 2026. Using the keywords “obese diabetic” and “obese diabetic AND exercise,” the search initially identified 987 records, including 906 from PubMed, 29 from ERIC and 52 from PEDro. After duplicate removal, 855 articles remained for screening. Titles and abstracts were then reviewed against predefined eligibility criteria, which led to the exclusion of 801 records. The full texts of 50 articles were subsequently retrieved and assessed, and 41 of these were excluded because they were not randomized or did not include a predefined outcome measure or intervention. In total, nine randomized controlled trials met the criteria and were included in the qualitative synthesis.

The review was carried out following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and the authors registered the protocol with PROSPERO under registration number CRD420261296203. Eligibility criteria required that studies observe the effect of exercise in individuals with both obesity and diabetes, with full-text literature available in English from 2000 to January 2026. Research addressing conditions other than diabetes in obese patients, or conditions other than obesity in diabetic patients, was excluded. Participants receiving diet modification or any intervention apart from active exercise were also excluded, a restriction intended to isolate the specific contribution of exercise training to the measured outcomes.

The population across the nine trials consisted of 383 individuals with diabetes mellitus and obesity, with reported ages ranging from 34 to 63 years. All participants were classified as obese and diabetic. Three of the nine studies recruited male participants only.

Glycemic control emerged as the most frequently evaluated domain in the included trials. HbA1c, the glycated haemoglobin measure that reflects average blood glucose over preceding weeks, was reported in eight of the nine studies. Fasting glucose or fasting blood sugar was assessed in five studies, and insulin levels were evaluated in three. Measures of insulin resistance, primarily the Homeostasis Model Assessment of Insulin Resistance known as HOMA-IR, were reported in six of the nine studies. The review found that both aerobic and resistance training led to improvements in glycemic control, with consistent reductions in HbA1c, fasting glucose and insulin resistance compared with control conditions.

The physiological mechanisms behind these glucose-related improvements are described in the review’s discussion of the underlying biology. The improvement in insulin sensitivity and blood glucose control after exercise training occurs, according to the evidence synthesized, through better insulin signaling, increased glucose transport to active muscle fibers, activation of protein kinase B, and increased expression of GLUT4 proteins. These adaptations help muscles take up more glucose and use it for energy during physical activity. The review also notes that different types of exercise interventions showed significant reductions in fasting blood sugar, HbA1c, insulin levels and HOMA-IR during the training period, findings the authors state are consistent with earlier research reporting beneficial effects of exercise on glucose control and insulin sensitivity in individuals with type 2 diabetes.

Beyond glycemic outcomes, the review documented favorable changes in anthropometric and body composition measures. Body mass index was reported in five of the nine studies, body mass was assessed in two, and body composition parameters were reported in three. Aerobic exercise was more frequently associated with reductions in BMI, body mass and lipid profile parameters, while resistance training showed greater benefits for body composition and muscular strength in three of the nine studies. The review indicates that exercise training was effective in improving body composition, demonstrated by increases in fat-free mass and lean body mass, and that BMI, body weight and waist circumference showed favorable changes following endurance, resistance and aerobic exercise programs. Low to moderate intensity exercise has been found to be effective in increasing fat oxidation in skeletal muscles, which the authors note ultimately contributes to greater fat loss.

Lipid profile outcomes were also frequently evaluated across the included trials. Total cholesterol, high-density lipid and low-density lipid measures were assessed in five of the nine studies, and triglycerides were evaluated in two. Significant training effects were noted for all groups receiving exercise training regarding adaptations to lipid profiles after the intervention period. Previous studies have reported reductions in cholesterol, LDL and triglyceride levels, along with increases in HDL, following various types of exercise training. The improvement in lipid profile after physical training may be related to increased expression of PPARγ and PGC-1α messenger RNA in muscle and adipose tissue, as suggested by one of the studies cited in the review. Liver function, assessed using alanine transaminase, was reported in two of the nine studies.

Inflammatory markers were examined in several of the included trials. Tumour necrosis factor-alpha and interleukin-6 were each reported in three of the nine studies, while interleukin-2, interleukin-4 and C-reactive protein were assessed in one study, and interleukin-8 was reported in one study. Reductions in inflammatory markers, particularly TNF-alpha and IL-6, were reported following aerobic exercise interventions in three of the nine studies. The review discusses possible mechanisms for these anti-inflammatory effects, noting that previous work has suggested the decrease in inflammatory markers after aerobic exercise may be mediated by improvement in psychosocial factors or by beta-adrenergic receptor mechanisms, all of which may improve insulin resistance and endothelial dysfunction. The authors also reference an animal study showing significant reduction in the expression of IL-6 and TNF-alpha in the pancreatic islets of diabetic rats that performed regular exercise, suggesting that exercise reduces inflammation, though this finding comes from animal rather than human research.

Aerobic capacity was less frequently assessed across the trials, with VO2 peak reported in three of the nine studies. Improvements in aerobic capacity were observed in studies incorporating aerobic or combined training protocols. The review notes that the increase in aerobic capacity is linked with improvement in muscle fiber capillary density and cardiac function, which lead to better oxygen delivery and maximal utilization of oxygen by the muscle during training. Endurance exercise training was also seen to reduce blood glycated haemoglobin levels, LDL-cholesterol concentrations and body weight, and to increase VO2 peak. The authors acknowledge limitations in their synthesis, including diverse treatment approaches across the included studies and a lack of subgroup analysis considering exercise types and their intensity, as well as the restriction to English-language randomized controlled trials. Despite these constraints, the review concludes that exercise training is effective for improvement in glycemic control, insulin resistance, anthropometric measures, body composition, lipid profile, inflammatory markers and aerobic capacity, supporting a beneficial role for exercise in improving physical and physiological functions in obese patients with diabetes mellitus.

Subject of Research: Effects of exercise training on physical and physiological functions in obese individuals with diabetes

Article Title: Effect of exercise on physical and physiological functions in obese diabetics: a systematic review

Article References: Singla, D., Khan, S., & Zafar, T. (2026). Effect of exercise on physical and physiological functions in obese diabetics: a systematic review. Bulletin of Faculty of Physical Therapy, 31(1), Article 29. https://doi.org/10.1186/s43161-026-00365-8

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DOI: 10.1186/s43161-026-00365-8

Keywords: systematic review, obesity, diabetes mellitus, exercise training, glycemic control, aerobic training, resistance training, HbA1c, insulin resistance, body composition, inflammatory markers, aerobic capacity