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

Abstract

Objective: Our 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 methods: Data 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 > or =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 (microU/ml)] x [fasting plasma glucose (mmol/L)]/22.5}.

Results: The 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.

Conclusions: Diabetes, impaired fasting glucose, and insulin resistance are common in the United States and their prevalence continues to increase.