The presence of diabetes is known as a major risk factor for cardiovascular mortality after acute myocardial infarction (AMI). Decreased exercise capacity is also independent poor prognostic factor for all-cause cardiovascular mortality in patients referred to a rehabilitation program after AMI. This study aim to investigate the difference of exercise capacity between diabetic (DM) and non-diabetic (non-DM) patients with AMI in cardiac rehabilitation (CR).

This retrospective study consisted of patients referred for CR after percutaneous coronary intervention from October 2010 to December 2015. Two hundred and twenty three patients who continued follow-up for 3 months after initiation of CR were enrolled. All patients (56 with DM and 167 without DM) participated in 12-week CR program. ETT was performed by modified Bruce protocol (mBP) at the initiation of CR, 6 weeks and 3 months after initiation of CR. We measured resting heart rate, maximum heart rate, resting systolic blood pressure, metabolic equivalents of tasks (METs), submaximal rate pressure product at stage 3 of mBP, total exercise time (TET), and peak oxygen consumption (peakVO₂). The parameters of exercise capacity were peakVO₂, METs and TET.

At initiation of CR, the DM group had significantly lower exercise capacity in TET, peak VO₂, and METs than did the non-DM group. Although both of two groups showed significantly improved exercise capacity after completing phase II CR, the DM group did not show statistically significant improvement of METs and peak VO₂ at 6 weeks after initiation of CR. Still, The DM group had significantly lower exercise capacity than non-DM group after completing phase II CR.

Even though exercise capacity had improved over time after completing CR regardless of presence of DM, Exercise capacity improved more slowly in DM group than in non-DM group. DM group had lower exercise capacity than did the non-DM group all the time of CR.