Early signs of atherosclerosis are associated with insulin resistance in non-obese adolescent and young adults with type 1 diabetes

Background: Patients with type 1 diabetes have a substantial risk of developing cardiovascular complications early in life. We aimed to explore the role of insulin sensitivity (S-i) as an early factor of atherosclerosis in young type 1 diabetes vs. non-diabetic subjects. Methods: Forty adolescent and young adult individuals (20 type 1 diabetics and 20 non-diabetics), age 14-20 years, without characteristics of the metabolic syndrome, participated in this cross-sectional study. After an overnight fast, S-i was measured by hyperinsulinemic euglycemic clamp (40 mU/m(2)) and calculated by glucose infusion rate (GIR). Carotid intima-media thickness (cIMT) was measured in the common carotid artery with high-resolution ultrasonography. Risk factors of atherosclerosis (Body mass index [BMI], waist circumference, systolic blood pressure [sBP], triglycerides, low HDL-cholesterol and HbA(1c)) were also investigated. Results: cIMT was increased (0.52 +/- 0.1 vs. 0.47 +/- 0.1 mm, P < 0.01), whereas GIR was decreased (5.0 +/- 2.1 vs. 7.1 +/- 2.2 mg/kg/min, P < 0.01) in type 1 diabetics vs. non-diabetics. The differences in cIMT were negatively associated with S-i (r = -0.4, P < 0.01) and positively associated with waist circumference (r = 0.34, P = 0.03), with no such associations between BMI (r = 0.15, P = 0.32), sBP (r = 0.09, P = 0.58), triglycerides (r = 0.07, P = 0.66), HDL-cholesterol (r = 0.10, P = 0.55) and HbA(1c) (r = 0.24, P = 0.13). In a multivariate regression model, between cIMT (dependent) and group (explanatory), only adjustment for S-i affected the significance (beta = 0.08, P = 0.11) vs. (beta = 0.07, P < 0.01) for the whole model. No interaction between cIMT, groups and S-i was observed. Conclusions: cIMT is increased and associated with insulin resistance in adolescent, non-obese type 1 diabetic subjects. Although, no conclusions toward a causal relationship can be drawn from current findings, insulin resistance emerges as an important factor reflecting early signs of atherosclerosis in this small cohort.