Purpose: Diabetes increases mortality after myocardial infarction, but participation in cardiac rehabilitation (CR) reduces this risk. Our objectives were to examine whether attendance at CR and changes in cardiorespiratory fitness differed according to diabetic status and sex.
Methods: Retrospective cohort study of patients referred for CR in Calgary between 1996 and 2010. Cardiorespiratory fitness in metabolic equivalents (METs) was estimated by maximal exercise testing at baseline, at the end of the 12-wk CR program, and 1-yr after CR.
Results: Among 7036 nondiabetic and 1546 diabetic patients who started, 84.9% of nondiabetic versus 79.5% of diabetic patients completed CR (P < 0.0001). The difference between diabetic and nondiabetic patients was greater in women (81.7% vs 72.1%, P < 0.0001) than that in men (86.0% vs 82.5%, P = 0.004). Patients without diabetes were more likely to return for the 1-yr assessment (53.7% vs 42.7%, P < 0.0001), and nondiabetic women were more likely than diabetic women to attend the 1-yr follow-up (44.3% vs 31.7%, P < 0.0001). Change in cardiorespiratory fitness from baseline to 12 wk was +1.0 METs in nondiabetic men, +0.9 METS in diabetic men, +0.9 METs in nondiabetic women, and +0.7 METs in diabetic women (within-group change; P = 0.0009). Changes in cardiorespiratory fitness at 1 yr compared with baseline were +0.9, +0.6, +0.9, and +0.5 METS, respectively (within-group change, P = 0.0001).
Conclusions: Patients with diabetes, especially females, were less likely than patients without diabetes to complete CR and attend follow-up. Among patients who attended 1-yr follow-up, changes in cardiorespiratory fitness were not as well maintained in diabetic patients as in nondiabetic patients. Identifying barriers and targeting CR adherence interventions to patients with diabetes may help improve outcomes.