Aim/hypothesis  

We determined the effect of exercise training on insulin sensitivity and muscle lipids (triglyceride [TG_m] and long-chain fatty acyl CoA [LCACoA] concentration) in patients with Type 2 diabetes.

Methods  

Seven patients with Type 2 diabetes and six healthy control subjects who were matched for age, BMI, % body fat and VO₂peak participated in a 3 days per week training program for 8 weeks. Insulin sensitivity was determined pre- and post-training during a 120 min euglycaemic-hyperinsulinaemic clamp and muscle biopsies were obtained before and after each clamp. Oxidative enzyme activities [citrate synthase (CS), -hydroxy-acyl-CoA (-HAD)] and TG_m were determined from basal muscle samples pre- and post training, while total LCACoA content was measured in samples obtained before and after insulin-stimulation, pre- and post training.

Results  

The training-induced increase in VO₂peak (~20%, p<0.01) was similar in both groups. Compared with control subjects, insulin sensitivity was lower in the diabetic patients before and after training (~60%; p<0.05), but was increased to the same extent in both groups with training (~30%; p<0.01). TG_m was increased in patients with Type 2 diabetes (170%; p<0.05) before, but was normalized to levels observed in control subjects after training. Basal LCACoA content was similar between groups and was unaltered by training. Insulin-stimulation had no detectable effect on LCACoA content. CS and -HAD activity were increased to the same extent in both groups in response to training (p<0.001).

Conclusion/interpretation  

We conclude that the enhanced insulin sensitivity observed after short-term exercise training was associated with a marked decrease in TG_m content in patients with Type 2 diabetes. However, despite the normalization of TG_m to levels observed in healthy individuals, insulin resistance was not completely reversed in the diabetic patients.