Plasma nitric oxide concentrations are elevated in insulin-resistant healthy subjects

The goal of this study was to compare plasma nitric oxide (NO) concentratio ns in healthy subjects, defined as either insulin-resistant or insulin-sens itive on the basis of the plasma insulin response to a 75-g oral glucose ch allenge. For this purpose, 404 healthy subjects were divided into quartiles on the basis of the plasma insulin response to glucose, and 49 individuals were selected from the quartile with the lowest insulin response and 49 fr om the quartile with the highest insulin response. The two groups of 49 eac h were selected to be essentially identical in terms of age, gender distrib ution, body mass index (BMI), and waist to hip ratio (WHR). The quartile wi th the greatest insulin response also had a significantly higher plasma glu cose response to oral glucose, faster heart rate, higher blood pressure, an d the combination of higher triglyceride and lower high-density lipoprotein (HDL) cholesterol concentrations. In addition to the latter changes, previ ously shown to be associated with hyperinsulinemia, NO concentrations were also higher in the hyperinsulinemic group. It is speculated that this incre ase in the NO concentration in hyperinsulinemic and presumably insulin-resi stant, subjects represents a compensatory effort to overcome the untoward e ffects of insulin resistance and/or hyperinsulinemia. Copyright (C) 2000 by W.B. Saunders Company.