Effects of exercise-based cardiac rehabilitation for coronary heart disease combined with diabetes mellitus: a systematic review and meta-analysis

BACKGROUND: Cardiac rehabilitation (CR) reduces mortality and morbidity in coronary heart disease (CHD). Globally, CHD is the most common reason for referral to exercise-based cardiac rehabilitation (ExCR). However, diabetes mellitus (DM) is a major risk factor for CHD. We aimed to assess ExCR’s efficacy in patients with both DM and CHD. METHODS: A systematic literature search was conducted from inception to December 13, 2025, in the following electronic databases: PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang Database, VIP Database, and Chinese Biomedical Database (CBM). This review was registered with PROSPERO (Registration No: CRD42024592143). Data synthesis was performed using Stata SE and RevMan 5.3. Pooled estimates were calculated using both fixed-effect and random-effects models; the random-effects model was adopted as the primary analysis when substantial heterogeneity was present (I² ≥ 50%). Subgroup analyses, meta-regression, and sensitivity analyses were conducted to explore potential sources of heterogeneity and to assess the robustness of the primary findings. Statistical heterogeneity was assessed using the I² statistic. RESULTS: There were 18 trials involving 1669 patients in all. The exercise group reduced fasting blood glucose (FBG) (mean differences (MD) -1.08, 95% confidence interval (CI) -1.49 to -0.66, P < 0.00001), 2-hour postprandial blood glucose (PBG) (MD -1.59, 95% CI -2.43 to -0.75, P = 0.0002), glycosylated haemoglobin (HbA1c) (MD -0.47, 95% CI -0.54 to -0.41, P < 0.00001), total cholesterol (TC) (MD -0.65, 95% CI -0.89 to -0.41, P < 0.00001), triglycerides (TG) (MD -0.34, 95% CI -0.41 to -0.28, P < 0.00001), low-density lipoprotein (LDL) (MD -0.22, 95% CI -0.30 to -0.14, P < 0.00001) and improved left ventricular ejection fraction (LVEF) (MD 5.28, 95% CI 1.72 to 8.85; P = 0.004) and 6-minute walk test (6-MWT). Peak oxygen uptake (VO2peak) was not significantly impacted. CONCLUSION: This review suggests ExCR may improve glycolipid metabolism, 6-MWT, and LVEF in patients with both CHD and DM. However, these findings are tempered by limitations in the primary studies, and the effect on VO2peak remains unclear. The results highlight the need for further high-quality research to confirm the efficacy of ExCR in this population.