Is cardiorespiratory fitness a determinant of cardiomyopathy in the setting of type 2 diabetes?

OBJECTIVE: The aim of this study was to determine whether high fitness attenuates the defects in left ventricular (LV) structure, function and triglyceride (TG) content in patients with type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS: Patients (n = 74) with T2DM and ≥1 additional cardiac risk factor were recruited to participate in this cross-sectional study. Outcome measures of interest were LV structure and function by magnetic resonance imaging (MRI) and myocardial TG content by (1)H-magnetic resonance spectroscopy (MRS). The primary exposure variable was cardiorespiratory fitness defined by peak oxygen consumption scaled to fat-free mass (FFM; VO2peak-FFM). RESULTS: Mean age was 53.5 years; 42.9% were women and mean glycosylated haemoglobin (HbA1c) was 8.0% with the mean duration of T2DM 8.2 years. VO2peak-FFM was crudely associated with both LV end systolic (r = 0.35, p = 0.002) and diastolic volumes (r = 0.32, p = 0.004), but not with ejection fraction (r = -0.15, p = 0.206), myocardial TG (r = -0.04, p = 0.734) or early diastolic peak filling rate (PFR; r = -0.01, p = 0.887). In multiple linear regression analyses, among measures of LV structure/function, VO2peak-FFM was independently associated only with LV end-diastolic volume (EDV) (β = 1.037, p = 0.038). CONCLUSION: In individuals with T2DM at increased cardiovascular (CV) risk, cardiorespiratory fitness is not associated with LV morphology, function or myocardial TG content.