INTIMAL-MEDIAL THICKNESS OF THE CAROTID-ARTERY IN NONDIABETIC AND NIDDM PATIENTS - RELATIONSHIP WITH INSULIN-RESISTANCE

OBJECTIVE - The aim of this study was 1) to compare intimal-medial thi ckness (IMT) of the carotid artery in nondiabetic and NIDDM patients a nd 2) to evaluate the association of this early marker of atherosclero sis with several cardiovascular risk factors, including plasma insulin and insulin resistance. RESEARCH DESIGN AND METHODS - A total of 58 n ondiabetic and 56 NIDDM patients, randomly selected among those attend ing the outpatient Diabetes Clinic or the Clinic for Internal Medicine were examined. BMI, waist-to-hip ratio (WHR), blood pressure, glycohe moglobin (HbA(1c)), and fasting concentrations of plasma glucose, seru m lipids (total and HDL cholesterol, triglycerides), and serum insulin were measured. Insulin resistance was assessed by computing glucose d isappearance rate from plasma after intravenous insulin injection (K-i tt). IMT of the carotid artery was measured by ultrasonography. RESULT S - IMT was significantly higher in diabetic patients, and the differe nce remained highly significant after adjusting for sex, age, BMI, WHR , presence of hypertension and dyslipidemia, and smoking status (1.39 vs. 1.24 mm, common SD 0.12, P < 0.001). Univariate regression analyse s showed that IMT was negatively correlated with K-itt in either nondi abetic (r=-0.348, P < 0.01) or diabetic patients (r=-0.492, P < 0.001) . However, multiple regression analyses showed that IMT was independen tly associated with age and WHR in nondiabetic subjects, whereas in di abetic patients, IMT was independently predicted by K-itt and hyperten sion. These two variables explained similar to 62% and similar to 35% of the variability of IMT in nondiabetic and diabetic patients, respec tively. Plasma insulin was not independently associated with IMT in ei ther groups.CONCLUSIONS - These results indicate that 1) diabetes is c haracterized by a greater thickness of the carotid artery independentl y of other established risk factor of atherosclerosis, 2) early athero sclerosis is independently associated with insulin resistance in diabe tic but not in nondiabetic patients, 3) central adiposity is an indepe ndent predictor of IMT in nondiabetic individuals.