In 2005–2006, an oral glucose tolerance test (OGTT) was added to NHANES,which had not been performed since NHANES 1988–1994. Whereas elevated FPG is determined more by impaired hepatic insulin resistance, elevated 2-h plasma glucose from an OGTT is determined predominantly by peripheral insulin resistance (4,6). The OGTT aids in
detecting the total burden of diabetes and also impaired glucose tolerance (IGT).
Two-hour plasma glucose values are more sensitive in the elderly (7), an increasing
proportion of the U.S. population. IGT also predicts diabetes and is more commonly associated with cardiovascular disease risk factors and events than IFG (4,8).