Objective: To better understand the cardiac limitations during exercise in adolescents with type 2 diabetes mellitus (T2DM), we measured left ventricular performance with magnetic resonance imaging (MRI) during exercise in diabetic and nondiabetic adolescents.
Research design and methods: Thirteen subjects with T2DM, 27 overweight/obese nondiabetic (ObeseND) subjects, and 19 nondiabetic nonobese control subjects were recruited. Cardiac (left ventricular) MRI scans were performed at rest and during submaximal exercise.
Results: Vo2 peak indexed to fat-free mass was reduced in T2DM and ObeseND subjects compared with control subjects (P < 0.0001). Indexed cardiac output increased less during exercise and was 20% lower in T2DM subjects due to reduced stroke volume. This was a consequence of reduced ventricular filling with smaller end-diastolic volume, which decreased further during exercise in T2DM subjects, but not in ObeseND or control subjects. End-systolic volume was also smaller in T2DM subjects. These changes were associated with increased resting and exercise diastolic blood pressure, and total peripheral resistance in T2DM subjects.
Conclusions: Independently of obesity, T2DM impairs cardiac function during exercise in adolescents.