Every move counts: Acute effects of sedentary breaks on glucose and lipid metabolism in middle-aged and older adults based on a multi-level meta-analysis

Prolonged sedentary behavior contributes to impaired glucose and lipid metabolism, particularly in middle-aged and older adults who are more vulnerable to metabolic decline. However, most evidence comes from mixed-age populations, and specific guidance on the optimal frequency, intensity, and type of sedentary breaks remains unclear. This study aims to evaluate the acute metabolic effects of sedentary breaks in middle-aged and older adults and identify moderators. A systematic search of PubMed, Web of Science, and Cochrane Library databases (through August 2025). Three-level random-effects meta-analyses were conducted to account for effect size dependency, with subgroup and meta-regression analyses exploring potential moderators. Interrupting prolonged sitting significantly reduced glucose (Hedges’ g = –0.62, 95 % CI: –0.92 to –0.31, p < 0.001) and insulin responses (g = –0.66, 95 % CI: –1.01 to –0.30, p = 0.001), with moderate-to-large effect sizes and substantial heterogeneity (I² > 79 %). Subgroup analyses identified significantly greater glucose-lowering effects in participants with high glucose (g = –1.05), type 2 diabetes mellitus (T2D) (g = –0.88), and healthy adults (g = –0.41), and the strongest insulin-lowering effects in those with dysglycemia (g = –1.95), followed by healthy adults (g = –0.65) and those with T2D (g = –0.68). Both resistance training and walking yielded robust improvements in glucose (g = –0.69 to –0.73) and insulin outcomes (g = –0.64 to –0.92), while cycling and standing showed no significant effects. Measurement type also moderated effects, with larger improvements for incremental AUC, glycemic variability, and total AUC. Meta-regression revealed that higher BMI (β = –0.096, p = 0.011) and longer activity bout duration (β = –0.307, p = 0.013) were significantly associated with greater insulin reductions, suggesting a dose–response relationship and enhanced responsiveness in metabolically at-risk individuals. No significant moderators were identified for glucose effects. In contrast, no significant effects were observed for lipid outcomes (Hedges’ g = –0.33, 95 % CI: –0.77–0.11, p = 0.15). Overall risk of bias was low in 85 % of studies, and publication bias was minimal across outcomes. The certainty of evidence was rated moderate for insulin, low for glucose, and very low for lipid outcomes, largely due to study heterogeneity, imprecision, and inconsistent findings. Brief activity breaks (2–5 min) interspersed every 30–60 min can acutely improve glucose and insulin regulation in middle-aged and older adults, particularly those at metabolic risk. These findings support integrating tailored sedentary break strategies into public health guidelines, while also highlighting the need to combine them with structured exercise for broader cardiometabolic benefits.