Trends in hyperinsulinemia among nondiabetic adults in the U.S.

OBJECTIVE Insulin resistance and compensatory hyperinsulinemia have been proposed as increasing risk for a variety of abnormalities and clinical syndromes, including type 2 diabetes and cardiovascular disease. Our aim was to assess the trends in the mean concentrations of fasting serum insulin and the prevalence of hyperinsulinemia among nondiabetic adults during the periods of 1988-1994 and 1999-2002 in the U.S. RESEARCH DESIGN AND METHODS We conducted analyses of data among men and nonpregnant women without diabetes aged >/=20 years from the Third National Health and Nutrition Examination Survey (NHANES III; 1988-1994; n = 7,926) and NHANES 1999-2002 (n = 2,993). Both surveys were designed to represent the noninstitutionalized civilian U.S. population. We calculated age-adjusted mean concentrations of fasting insulin and the prevalence of hyperinsulinemia defined using the 75th percentile of fasting insulin among nondiabetic individuals as the cutoff value. RESULTS The geometric mean concentrations of fasting insulin increased by approximately 5% from 1988-1994 to 1999-2002 among nondiabetic adults aged >/=20 years in the U.S. Mexican-American men, men and women aged 20-39 years, and non-Hispanic white women had a greater relative increase in the mean concentrations of fasting insulin than their counterparts. The prevalence of hyperinsulinemia increased by 35.1% overall (38.3% among men and 32.1% among women). CONCLUSIONS In parallel with the obesity epidemic, concentrations of fasting insulin and prevalence of hyperinsulinemia have increased remarkably among nondiabetic U.S. adults.