Lack of effect of simvastatin on insulin sensitivity in Type 2 diabetic patients with hypercholesterolaemia: results from a double-blind, randomized, placebo-controlled crossover study.

AIMS: To evaluate the effects of simvastatin on serum lipids and insulin sensitivity in Type 2 diabetic patients with hypercholesterolaemia. METHODS: A double-blind, randomized, placebo-controlled and two-period crossover study. After a 2-month run-in, 19 eligible Type 2 diabetic patients with hypercholesterolaemia were randomized to receive either simvastatin or placebo for 3 months, exchanging their treatment thereafter for another 3 months. Blood samples were taken in month 0 and at monthly intervals to measure serum lipids and indices of glycaemic control. An euglycaemic insulin clamp was performed in months 0, 3 and 6 to assess change of insulin sensitivity. The amount of glucose infused during 90-120 min of the clamp (M), and the mean values of serum insulin during 90-120 min (I) were measured. The M and M/I ratio were used to represent the in vivo insulin sensitivity of the subject. RESULTS: Simvastatin significantly reduced serum total cholesterol (TC) by 23+/-18% and low density lipoprotein-cholesterol (LDL-C) by 30+/-26%. It did not alter glycaemic control. The M-values and M/I ratios were similar in both groups in each period and no drug effect on insulin sensitivity could be identified. CONCLUSIONS: Simvastatin significantly reduced the serum TC and LDL-C levels without alteration of insulin sensitivity in Type 2 diabetic patients with hypercholesterolaemia.