Relationships between cardiorespiratory fitness, metabolic control, and fat distribution in type 2 diabetes subjects.

Factors contributing to the reduced cardiorespiratory fitness typical of sedentary subjects with type 2 diabetes are still largely unknown. In this study we assessed the relationships between cardiorespiratory fitness and abdominal and skeletal muscle fat content in 39 untrained type 2 diabetes subjects, 27 males and 12 females (mean±SD age 56.5±7.3 yr, BMI 29.4±4.7 kg/m2). Peak oxygen uptake (VO2peak) and ventilatory threshold (VO2VT) were assessed by maximal cycle ergometer exercise test, insulin sensitivity by euglycemic-hyperinsulinemic clamp, and body composition by dual-energy x-ray absorptiometry. Magnetic resonance imaging was used to evaluate visceral (VAT), total subcutaneous (SAT), superficial (SSAT) and deep (DSAT) sub-depots of subcutaneous abdominal adipose tissue, and sagittal abdominal diameter (SAD), as well as femoral quadriceps skeletal muscle fat content.In univariate analysis, both VO2peak and VO2VT were inversely associated with BMI, total fat mass, SAT, SSAT and sagittal abdominal diameter. VO2peak was also inversely associated with skeletal muscle fat content. A significant direct association was observed between VO2VT and insulin sensitivity. No associations between cardiorespiratory fitness parameters and metabolic profile data were found. In multivariable regression analysis, after adjusting for age and gender, VO2peak was independently predicted by higher HDL-cholesterol, and lower SAD and skeletal muscle fat content (R2=0.64, p<0.001), whereas VO2VT was predicted only by sagittal abdominal diameter (R2=0.48, p=0.025).In conclusion, in untrained type 2 diabetes subjects, peak oxygen uptake is associated with sagittal abdominal diameter, skeletal muscle fat content and HDL-cholesterol levels. Future research should target these features in prospective intervention studies