Effects of exercise intervention on glucose and lipid metabolism in patients with type 2 diabetes mellitus complicated by non-alcoholic fatty liver disease: a three-level meta-analysis.

OBJECTIVES

This systematic review and three-level meta-analysis evaluated the effects of exercise interventions on glycemic control, lipid metabolism, body composition/fat distribution, and liver function in patients with type 2 diabetes mellitus (T2DM) complicated by non-alcoholic fatty liver disease (NAFLD), and examined potential sources of heterogeneity relevant to individualized exercise prescription.

METHODS

Randomized controlled trials were searched in Web of Science, PubMed, Cochrane Library, EBSCO, Embase, and CNKI from database inception to February 2026. The review followed PRISMA 2020 and used a three-level meta-analytic model to account for dependent effect sizes extracted from the same study. A priori subgroup analyses were conducted by exercise modality, and meta-regression was used to explore heterogeneity.

RESULTS

Twenty-four studies involving 2,578 participants were included. Overall, exercise reduced BMI (Hedges' g = -0.36, p < 0.001), FPG (Hedges' g = -0.42, p < 0.001), HbA1c (Hedges' g = -0.52, p < 0.001), HOMA-IR (Hedges' g = -0.48, p < 0.001), LDL-C (Hedges' g = -0.36, p = 0.001), TG (Hedges' g = -0.45, p < 0.001), ALT (Hedges' g = -0.41, p < 0.001), AST (Hedges' g = -0.38, p < 0.001), and GGT (Hedges' g = -0.40, p < 0.001), and increased HDL-C (Hedges' g = 0.28, p = 0.009). Modality-specific analyses suggested that MICT may be more favorable for FPG, LDL-C, VAT, and HFC, whereas HIIT showed larger effects for HbA1c, HOMA-IR, TG, ALT, and GGT. Heterogeneity was substantial for TG, ALT, AST, HbA1c, and GGT in the primary analyses; however, sensitivity analyses reduced I 2 below 50% without materially altering the pooled effects. Evidence for resistance training was limited by the small number of studies and should be interpreted cautiously. Meta-regression suggested that medication status and exercise frequency may be potential contributors to between-study heterogeneity.

CONCLUSION

Exercise, particularly aerobic exercise, appears to be a beneficial adjunctive strategy for improving metabolic and liver-related outcomes in patients with T2DM and NAFLD. Because clinical heterogeneity, medication use, dietary co-interventions, and study quality may influence the estimates, modality-specific conclusions should be applied cautiously and individualized according to patients' metabolic profile, comorbidities, and exercise tolerance.

SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/view/CRD420261327724, identifier CRD420261327724.