S: Differences in insulin resistance in nondiabetic subjects with isolated impaired glucose tolerance or isolated impaired fasting glucose. Diabetes 53:1549–1555

Both impaired glucose tolerance (IGT) (as defined by the 1985 World Health Organization criteria) and im-paired fasting glucose (IFG) (as defined by the 1997 American Diabetes Association criteria) represent in-termediate metabolic states between normal and dia-betic glucose homeostasis. Cardiovascular disease may be related to postglucose load rather than fasting gly-cemia, i.e., IGT rather than IFG. We hypothesized that subjects with IGT may be more insulin resistant and have higher levels of common cardiovascular risk fac-tors than those with isolated IFG. In the Insulin Resis-tance Atherosclerosis Study (IRAS), we studied Si and first-phase insulin secretion (acute insulin response [AIR]), as derived from a frequently sampled intrave-nous glucose tolerance test, as well as common cardio-vascular risk factors in four different glucose tolerance categories (NFG/NGT [n 654], NFG/IGT [n 255], IFG/NGT [n 59], and IFG/IGT [n 102]) among nondiabetic subjects. Subjects with isolated postchal-lenge hyperglycemia (NFG/IGT) had lower Si (means SE: 2.10 0.04 vs. 2.59 0.13 104 min1 U1 ml1; P 0.005), lower proinsulin levels (34.4 1.8 vs