Prevalence and trends of insulin resistance, impaired fasting glucose, and diabetes

ObjectiveOur aim was to measure the prevalence and time trends of diabetes, impaired fasting glucose, and insulin resistance in the United States during the periods 1988–1994 and 1999–2002.Materials and methodsData were derived from two nationally representative samples of the adult U.S. population collected as part of the National Health and Nutrition Examination Surveys of 1988–1994 (n=18,800) and 1999–2002 (n=10,283). We compared these two samples with respect to the following outcomes: previously diagnosed diabetes defined by self-report; undiagnosed diabetes defined as fasting plasma glucose ≥126 mg/dl; impaired fasting glucose defined as fasting plasma glucose 100–125 mg/dl; and insulin resistance calculated using the homeostasis model assessment as {[fasting serum insulin (μU/ml)]×[fasting plasma glucose (mmol/L)]/22.5}.ResultsThe age- and sex-adjusted prevalence of diagnosed diabetes increased from 5.5% in 1988–1994 to 6.8% in 1999–2002 (change 1.3%, 95% confidence interval 0.5–2.1). Little change occurred in the adjusted prevalence of undiagnosed diabetes (from 3.0 to 3.0%) and impaired fasting glucose (from 26.2 to 26.9%). Mean insulin resistance and the proportion with high insulin resistance increased significantly both among normoglycemic persons (mean: from 2.0 to 2.2; proportion >2.35: from 26.2 to 32.2%) and among persons with undiagnosed diabetes or impaired fasting glucose (mean: from 4.0 to 4.5; proportion >4.4: from 24.8 to 31.1%). In 1999 to 2002, diagnosed and undiagnosed diabetes were most common in non-Hispanic blacks, whereas impaired fasting glucose was most common in Mexican Americans.ConclusionsDiabetes, impaired fasting glucose, and insulin resistance are common in the United States and their prevalence continues to increase.