Endothelial function varies according to insulin resistance disease type

OBJECTIVE - We examined the relationship between insulin resistance and vascular function in three insulin-resistant states (type 2 diabetes, non-HIV lipodystrophic diabetes, and nondiabetic polycystic ovary syndrome [PCOS]) and in healthy control subjects. RESEARCH DESIGN AND METHODS - The population included 12 women with type 2 diabetes, 6 with lipodystrophic diabetes, 10 with PCOS, and 19 healthy female subjects. Metabolic measures included insulin sensitivity by the homeostasis model assessment, lipids, free fatty acids, and adiponectin. High-resolution B-mode ultrasound was used to determine endothelium-dependent and -independent vasodilation. RESULTS - Type 2 diabetic, liposdystrophic, and PCOS subjects were insulin resistant compared with control subjects (P = 0.001). Flow-mediated vasodilation was reduced in diabetic (3.4 ± 1.3%) compared with control (7.3 ± 1.1%) subjects but not in lipodystrophic (7.7 ± 1.2%) or PCOS (9.9 ± 0.7%) subjects (P = 0.005). Nitroglycerin-mediated vasodilation was attenuated in both diabetic (15.2 ± 2.0%) and lipodystrophic (16.7 ± 3.6%) subjects compared with healthy control (24.6 ± 2.4%) and PCOS (23.2 ± 1.8%) subjects (P = 0.019). Insulin resistance, free fatty acids, adiponectin, or C-reactive protein did not associate with vascular dysfunction. CONCLUSIONS - Among these different types of patients with insulin resistance, we found abnormal endothelium-dependent vasodilation only in the patients with type 2 diabetes. We postulate that variations in the mechanism of insulin resistance may affect endothelial function differently than glucose homeostasis.