Exercise is recommended for improving glycaemic control in patients with type 2 diabetes.
The recommendation is strong because exercise has many other beneficial health outcomes, has low costs, and rarely has any harms. Improvement in glycaemic control is very likely to improve patient-important outcomes by preventing or postponing complications of diabetes.
A meta-analysis 3 included 106 studies with 7438 patients with type 2 diabetes (T2D). 6 exercise modalities, except unsupervised aerobic/resistance exercise, significantly reduced glycosylated haemoglobin (HbA1c), with mean differences (MDs) ranging from 0.71 (95% CI 0.34 to 1.08) to 0.34 (95% CI 0.17 to 0.52), low to high certainty, in comparison with no exercise. Supervised aerobic/resistance exercise improved glycaemic control, body weight, blood pressure, and blood lipid profiles compared with no exercise.
A meta-analysis 5 included 37 studies with 2208 patients with T2D. Both supervised aerobic and supervised resistance exercises showed a significant reduction in HbA1c compared to no exercise (0.30% lower, 0.30% lower, respectively), however, there was a less reduction when compared to combined exercise (0.17% higher, 0.23% higher). Supervised aerobic as well as supervised resistance also presented more significant improvement than no exercise in fasting plasma glucose, total cholesterol, triacylglycerol, and low-density lipoprotein cholesterol. Supervised aerobic exercise was more powerful in improving HbA1c and weight loss than unsupervised aerobic (HbA1c: 0.60% lower; weight loss: 5.02 kg lower) and unsupervised resistance (HbA1c: 0.53% lower) exercises.
Another meta-analysis 4 assessing associations of structured exercise training (aerobic, resistance, or both) in T2D included 47 RCTs with 8538 patients. Structured exercise decreased HbA1c (-0.67%, 95% CI -0.84% to -0.49%; 23 trials) compared with control. Declines in HbA1c compared with control were -0.73% (95% CI -1.06% to -0.40%) in structured aerobic exercise; -0.57% (95% CI -1.14% to -0.01%) in structured resistance training; and -0.51% (95% CI -0.79% to -0.23%) in both combined. Structured exercise durations of more than 150 minutes per week were associated with HbA1c reductions of 0.89%, while structured exercise durations of 150 minutes or less per week were associated with HbA1c reductions of 0.36%. Combined physical activity advice and dietary advice was associated with decreased HbA1c (-0.58%; 95% CI -0.74% to -0.43%) as compared with control. Physical activity advice alone was not associated with HbA1c changes.
A Cochrane review [Abstract] 1 included 14 studies with a total of 377 subjects. Compared with the control, the exercise intervention significantly improved glycaemic control as indicated by a decrease in glycated haemoglobin levels of 0.6% (-0.6 % HbA1c, 95% CI -0.9 to -0.3). The exercise intervention significantly increased insulin response (131 AUC, 95% CI 20 to 242) (one trial), and decreased plasma triglycerides (-0.25 mmol/l, 95% CI -0.48 to -0.02). No significant difference was found between groups in quality of life (one trial), plasma cholesterol or blood pressure. The decrease of HbA1c was achieved over relatively short periods of time (the shortest studies were of eight weeks duration, and there were only two studies with an intervention of six months or more).
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