SKELETAL MUSCLE LIPID CONTENT AND INSULIN RESISTANCE

Abstract

PURPOSE This cross-sectional study assessed whole-body insulin sensitivity (by euglycemic-hyperinsulinemic clamp), skeletal muscle triglycerides (IMTG), long-chain acyl CoA (LCACoA) content and fatty acid (FA) transporter protein content in 8 patients with type 2 diabetes (TYPE 2), 6 healthy control subjects matched for age, BMI, % body fat and VO2peak (OLD), 9 well-trained athletes (TRAINED) and 4 age-matched controls (YOUNG). METHODS Muscle biopsies from the v. lateralis were taken prior to and after a 2 h clamp. Oxidative enzyme activities, FA transporters (FAT/CD36 and FABPpm) and IMTG were determined from resting muscle samples, while total LCACoA content was assessed pre- and post-insulin stimulation. RESULTS Whole body insulin-stimulated glucose disposal was lower in TYPE 2 (p < 0.05). Citrate synthase activity was increased in TRAINED (p < 0.05), while βHAD activity was higher in TRAINED compared to TYPE 2 (94%) and OLD (76%). There was no difference in FAT/CD36 protein content between groups. FABPpm protein was decreased in OLD compared to TYPE 2 and YOUNG (p < 0.05). IMTG was elevated in TYPE 2 compared to OLD, YOUNG and TRAINED (p < 0.05). Basal skeletal muscle LCACoA content did not differ between groups, or after insulin-stimulation. CONCLUSION Despite marked differences in whole-body insulin sensitivity, skeletal muscle oxidative enzyme activity and IMTG, total LCACoA content and the FA transporter proteins FAT/CD36 and FABPpm were similar between type 2 diabetics and well-trained endurance athletes. Supported by a grant from EFFEM Foods (Mars) Australia.