Dose-Dependent Effect of Supervised Aerobic Exercise on HbA_1c 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 (HbA_1c). We searched PubMed, Scopus, and Web of Science to May 2021 for randomized trials with an intervention period of 12 weeks or longer evaluating the effect of SAT on HbA_1c 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 HbA_1c by - 0.22 percentage point (95% CI - 0.29 to - 0.15; GRADE = strong). Levels of HbA_1c decreased proportionally with the increase in the duration of moderate to vigorous-intensity SAT to 100 min/week (mean difference_{100 min/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 30 min/week of moderate to vigorous aerobic exercise can exert a significant effect on HbA_1c, with the highest effect observed from 100 min/week and above. However, exercise durations above 100 min/week seem ineffective for further reductions. PROSPERO (CRD42021257251).