Effects of short-bout accumulated physical activity and sedentary-break interventions on continuous glucose monitoring metrics in adults with type 2 diabetes: A systematic review and meta-analysis.

OBJECTIVE: Glycated hemoglobin does not fully capture postprandial hyperglycemia or intraday glycemic fluctuation, whereas continuous glucose monitoring (CGM) characterizes mean glucose, hyperglycemic exposure, and glycemic variability. Short-bout accumulated physical activity and sedentary-break interventions are low-burden strategies that can be integrated into daily routines, but their overall effects on CGM-derived outcomes in adults with type 2 diabetes remain uncertain. We systematically reviewed and quantitatively synthesized these effects. METHODS: We searched 11 bibliographic and registry sources from inception to 29 July 2026, after an initial eight-database search through 4 June 2026. Randomized and controlled crossover trials were eligible. We retained the original broad eligibility criteria and examined a narrower post-hoc intervention definition in sensitivity analysis. Paired mean differences and standard errors were extracted or reconstructed. Random-effects meta-analysis used restricted maximum likelihood with Hartung-Knapp-Sidik-Jonkman inference. When paired covariance was unavailable, r = 0.50 was used, with r = 0.25 and r = 0.75 sensitivity analyses. Risk of bias was assessed for specific results with crossover RoB 2 and certainty was assessed with GRADE. RESULTS: Thirteen studies were included; 10 studies (175 participants) contributed to the overall mean-glucose synthesis. Short-bout activity reduced mean glucose (MD = -0.71 mmol/L, 95% CI -1.28 to -0.13; p = 0.021), with considerable heterogeneity (I² = 91%; tau² = 0.55) and a prediction interval that included the null value (no effect) (-2.48 to 1.06). Intervention category did not explain heterogeneity (p = 0.628). All leave-one-out estimates remained significant; omitting Dempsey (2017) reduced I² to 5.8% and yielded MD = -0.33 mmol/L (95% CI -0.50 to -0.16). Mean amplitude of glycemic excursions (MAGE) favored activity, whereas glucose standard deviation (SD), coefficient of variation (CV), and time in range (TIR) were inconclusive. Hyperglycemia time was pooled only for compatible thresholds and windows. Certainty ranged from moderate to very low and was low for mean glucose. CONCLUSION: Short-bout accumulated physical activity may reduce CGM-derived mean glucose in adults with type 2 diabetes. Although effects remained favorable across correlation, model, arm-selection, and leave-one-out analyses, considerable heterogeneity and a prediction interval that included the null value (no effect) limit confidence in the effect expected in a new setting. Evidence for other glycemic outcomes and safety remains uncertain. SYSTEMATIC REVIEW REGISTRATION: www.crd.york.ac.uk/prospero, identifier CRD420261415265.