Change in exercise capacity after cardiac rehabilitation following coronary heart disease in patients with and without diabetes: A follow-up study

INTRODUCTION: Cardiac rehabilitation (CR) improves cardiovascular health and quality of life after coronary heart disease (CHD). However, it remains uncertain whether patients with diabetes achieve similar gains in exercise capacity as those without diabetes. METHODS: This cohort study included patients discharged from hospital following CHD between February 2019 and December 2022 who completed a 12-week CR programme at 18 community health centres. Exercise capacity was assessed using a symptom-limited bicycle ergometer test and reported as both absolute (mL O₂/min) and relative VO₂peak (mL O₂/kg/min). Differences in improvement were evaluated using multiple regression analyses, and the likelihood of achieving a minimal clinically important difference (MCID) of 3.5 mL O₂/kg/min was examined using binary logistic regression. RESULTS: Of the 2227 patients included, 437 (19.6 %) had diabetes. At both baseline and follow-up, patients with diabetes had significantly lower exercise capacity (p < 0.001). Although both groups improved significantly, gains were smaller among patients with diabetes (2.3 ± 2.4 vs. 2.9 ± 2.6 mL O₂/kg/min; p < 0.001). After adjustment, diabetes remained independently associated with smaller improvement (-0.42 mL O₂/kg/min; 95 % CI: -0.69 to -0.15; p = 0.002). The likelihood of achieving the MCID was also lower in the diabetes group (risk difference: -0.08; 95 % CI: -0.13 to -0.04; p < 0.001). CONCLUSION: Although patients with diabetes demonstrated improvements following CR, their gains in exercise capacity were smaller and less likely to be clinically meaningful compared with those without diabetes. These findings highlight the need for tailored CR strategies to optimise outcomes in this high-risk population.