Dose-Dependent Effect of Supervised Aerobic Exercise on HbA1c in Patients with Type 2 Diabetes: A Meta-analysis of Randomized Controlled Trials.

Abstract

Previous meta-analyses indicated that aerobic exercise can improve glycemic control. However, the optimum dose of exercise is still being discussed. The aim of this study was to examine the dose-dependent effect of supervised aerobic training (SAT) on glycated hemoglobin (HbA1c). We searched PubMed, Scopus, and Web of Science to May 2021 for randomized trials with an intervention period of 12weeks or longer evaluating the effect of SAT on HbA1c in adults with type 2 diabetes mellitus. Secondary outcomes included quality of life, change in hypoglycemic medications, and adverse events. A random-effects dose-response meta-analysis was conducted. The analysis of 26 trials with 1253 participants indicated that each 30-min/week SAT reduced HbA1c by - 0.22 percentage point (95% CI - 0.29 to - 0.15; GRADE = strong). Levels of HbA1c decreased proportionally with the increase in the duration of moderate to vigorous-intensity SAT to 100min/week (mean difference100min/week: - 0.96 percentage point, 95% CI - 1.25 to - 0.67), with flattening of the curve at higher duration. Aerobic exercise decreased antidiabetic medications by 13 per 100 patients (risk difference 0.13, 95% CI 0.02-0.23; 7 trials, n = 375; GRADE = moderate), and increased hypoglycemic reactions by 10 per 100 patients (risk difference: 0.10, 95% CI 0.03-0.17; 4 trials, n = 263; GRADE = low) and adverse events by 4 per 100 patients (risk difference: 0.04, 95% CI - 0.02 to 0.11; 2 trials, n = 236; GRADE = low). Limited evidence is available for quality of life. Every 30min/week of moderate to vigorous aerobic exercise can exert a significant effect on HbA1c, with the highest effect observed from 100min/week and above. However, exercise durations above 100min/week seem ineffective for further reductions. PROSPERO (CRD42021257251).