Diabetic Cardiovascular Autonomic Neuropathy: Insulin Resistance, Lipids and Simvastatin

Background: Treatment of diabetic cardiac autonomic neuropathy (CAN) is a complex process, that includes: lifestyle modification; reducing of insulin resistance (IR); optimal glycemic control; management of diabetic dyslipidemia; antioxidants; vitamins; treatment of myocardial metabolic abnormalities; thrombosis and others. The aim of study was to investigate the effects of simvastatin on insulin resistance and blood lipid profile parameters in patients with type 2 diabetes mellitus (DM) and the definite stage of cardiac autonomic neuropathy. Methods: The study involved 107 patients with type 2 DM among them 16 patients without CAN, 19 with subclinical stage of CAN and 72 with definite CAN. Median age of patients was 53.6±0.41 years, disease duration - 4.12±0.24 years and median glycated hemoglobin (HbA1c) - 7.01%±0.09%. The control group included 14 almost healthy people without DM. Patients with definite CAN were allocated into two treatment groups: 1st group - 22 patients received standard hypoglycemic therapy and simvastatin 20 mg/day; 2nd group - control (n = 15). The duration of the study was 3 mos. The concentrations of glucose, HbA1c, immunoreactive insulin (IRI) in the blood were determined. Lipid metabolism was assessed by the concentration of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG) measurements. The IR index (HOMA-IR), atherogenic coefficient (AC), TG/HDL-C parameters, and TG-glucose (TyG) index were calculated. Result: It was established that in patients with type 2 DM with subclinical stage of CAN there was statistically significant increase in the parameters of HbA1c, IRI, TC, TG and HOMA-IR, AC, TyG indices and decrease of TG/HDL-C and HDL-C compared to control; increase of IRI, TG, TG/HDL-C and TyG indices compared to patients with type 2 DM without CAN. The definite stage of CAN is characterized by an increase of HbA1c, IRI, TC, LDL-C levels and HOMA-IR, AC indices and a significant decrease in the concentration of HDL-C (compared to patients with subclinical CAN). As a result of our study, we found out that prescription of simvastatin to patients with definite stage of CAN was accompanied by a statistically significant decrease in the concentration of TC, LDL-C, TG and an increase in the content of HDL-C (compared to 2nd, control group). Conclusion: Obtained results justify the appropriateness of statins prescription to patients with type 2 DM and the definite stage of CAN.