Effects of simvastatin and atorvastatin administration on insulin resistance and respiratory quotient in aged dyslipidemic non-insulin dependent diabetic patients

One hundred and ninety-five aged (mean age: 67 +/- 4.8 years), non-insulin dependent diabetic patients underwent a randomised single-blind study for i nvestigating the effect of statin administration on insulin resistance and respiratory quotient. After 4 weeks run-in period, all patients were random ised in three groups: placebo (n = 67), simvastatin (10 mg/day) (n = 61) an d atorvastatin (5 mg/day) (n = 67). Each treatment period lasted 8 weeks. A t the beginning, after the run-in and at the end of the study, insulin resi stance was assessed by homeostasis model assessment (HOMA) index, while res piratory quotient (Rq) was evaluated by indirect calorimetry. Statins versu s placebo significantly lowered plasma total, LDL-, HDL-cholesterol and tri glyceride concentrations and improved insulin resistance and Rq and metabol ic control. Atorvastatin had a greater effect than simvastatin on plasma tr iglyceride concentration (- 26.3 +/- 3.1 vs. - 19.7 +/- 2.8%, P < 0.03), HO MA index (- 13.1 +/- 0.6 vs. - 9.1 +/- 0.9%, P<0.05), Rq (5.9 +/- 0.4 vs. 3 .1 +/- 0.5%, P < 0.05) and glycosylated haemoglobin ( - 11.2 +/- 0.3 vs. - 7.1 +/- 0.4%, P < 0.05). In the whole group of subjects (n = 195) and at th e end of the study, changes in plasma triglyceride concentrations were sign ificantly correlated with the change in the HOMA index (r = 0.44, P<0.001) and age and BMI adjusted-Rq (r = - 0.32, P < 0.005). Multivariate analyses demonstrated that decline in plasma triglyceride concentration was a signif icant determinant for explaining the effect of statin on insulin resistance and Rq. In conclusion our study demonstrates that statin administration is useful for controlling dyslipidemia in NIDDM patients and for improving th e metabolic control. With regard to this latter aim, atorvastatin seems to be more powerful than simvastatin. (C) 2000 Elsevier Science Ireland Ltd. A ll rights reserved.