Optimal time window of postprandial exercise in middle-aged and older adults with type 2 diabetes mellitus: a systematic review and meta-analysis

Postprandial hyperglycemia constitutes an independent risk factor for diabetic complications, particularly in middle-aged and older adults with type 2 diabetes mellitus (T2DM). Although exercise timing may critically modulate postprandial glycemic control, the optimal time window for this population remains to be established. To systematically evaluate the effect of postprandial exercise on glycemic control in middle-aged and older adults with type 2 diabetes mellitus (T2DM), and to provide evidence-based recommendations for optimal postprandial exercise timing. A systematic search of PubMed, Embase, Cochrane Library, and other databases was performed. Fourteen randomized crossover or parallel controlled trials involving 440 middle-aged and older patients with T2DM were included. The intervention was postprandial exercise. A random-effects meta-analysis was conducted, with subgroup analyses exploring the effects of exercise modality, timing, and disease duration on postprandial glucose area under the curve (AUC) and postprandial blood glucose levels. This study found that, compared with the control group, postprandial exercise significantly reduced both the glucose AUC (8 studies, 11 effect sizes; Hedges’ g = − 0.61; SE = 0.16; P < 0.05) and postprandial blood glucose levels (6 studies, 12 effect sizes; Hedges’ g = − 1.82; SE = 0.23; P < 0.05). Postprandial exercise contributed to improved acute glycemic control in middle-aged and older adults with T2DM. Notably, the non-aerobic-only exercise subgroup (e.g., passive stretching, resistance exercise, or combined exercise) demonstrated a more pronounced effect in reducing postprandial glucose AUC in this population. Although no statistically significant differences were observed across postprandial exercise timing subgroups for either glycemic outcome, the 30–90 min postprandial subgroup showed a numerically larger reduction in postprandial blood glucose effect sizes. Postprandial exercise can reduce postprandial blood glucose levels and the postprandial glucose AUC in middle-aged and older patients with type 2 diabetes. Non-aerobic-only exercise (e.g., passive stretching, resistance exercise, or combined exercise) appears to be more suitable for glycemic control in this population, although this finding remains preliminary. Initiating exercise within the 30–90 min postprandial window may be more effective in improving postprandial blood glucose. Not applicable.