Comparison of atorvastatin and simvastatin modulation on adiponectin and insulin resistance in non-diabetic dyslipidemic patients

INTRODUCTION: Statins are the first-line treatment of dyslipidemia but their use is associated with an increased risk of impaired glycemic control. In this study, the effects of atorvastatin and simvastatin on adiponectin levels and insulin resistance index were compared in non-diabetic dyslipidemic patients.
METHODS: Thirty-nine dyslipidemic non-diabetic outpatients were included in this study. The patients were prescribed with either simvastatin 20 mg or atorvastatin 20 mg. Blood sampling was carried out before and two months after statin treatments to measure the adiponectin, insulin, and fasting blood glucose (FBG) levels. The insulin resistance index was calculated based on the Homeostatic Model Assessment-Insulin Resistance (HOMA-IR).
RESULTS: Most patients had low baseline adiponectin levels (<3 µg/dl) and were not significantly changed after two months of atorvastatin or simvastatin treatment. The fasting insulin levels significantly increased in the simvastatin group (p=0.033), but not in the atorvastatin group. The HOMA-IR index was also increased in the simvastatin group from 1.89 ± 4.51 before to 2.72 ± 5.86 after treatment but did not reach statistical significance. Further analysis found a positive correlation between fasting insulin level and HOMA-IR value and the simvastatin group's adiponectin level (p=0.001).
DISCUSSION AND CONCLUSION: There is an indication that simvastatin, but not atorvastatin, stimulates an increase in fasting insulin levels after two months of treatments. The increase in the insulin resistance index correlates to the plasma level of adiponectin. Further study with a longer duration of observation is required to address this potential side effect.