Associations Between Trends in Race/Ethnicity, Aging, and Body Mass Index With Diabetes Prevalence in the United States A Series of Cross-sectional Studies

Background: The increase in the prevalence of diabetes over the past few decades has coincided with an increase in certain risk factors for diabetes, such as a changing race/ethnicity distribution, an aging population, and a rising obesity prevalence. Objective: To determine the extent to which the increase in diabetes prevalence is explained by changing distributions of race/ethnicity, age, and obesity prevalence in U. S. adults. Design: Cross-sectional, using data from 5 NHANES (National Health and Nutrition Examination Surveys): NHANES II (1976-1980), NHANES III (1988-1994), and the continuous NHANES 1999-2002, 2003-2006, and 2007-2010. Setting: Nationally representative samples of the U. S. non-institutionalized civilian population. Patients: 23 932 participants aged 20 to 74 years. Measurements: Diabetes was defined as a self-reported diagnosis or fasting plasma glucose level of 7.0 mmol/L (126 mg/dL) or more. Results: Between 1976 to 1980 and 2007 to 2010, diabetes prevalence increased from 4.7% to 11.2% in men and from 5.7% to 8.7% in women (P for trends for both groups < 0.001). After adjustment for age, race/ethnicity, and body mass index, diabetes prevalence increased in men (6.2% to 9.6%; P for trend < 0.001) but not women (7.6% to 7.5%; P for trend = 0.69). Body mass index was the greatest contributor among the 3 covariates to the change in prevalence estimates after adjustment. Limitation: Some possible risk factors, such as physical activity, waist circumference, and mortality, could not be studied because data on these variables were not collected in all surveys. Conclusion: The increase in the prevalence of diabetes was greater in men than in women in the U. S. population between 1976 to 1980 and 2007 to 2010. After changes in age, race/ethnicity, and body mass index were controlled for, the increase in diabetes prevalence over time was approximately halved in men and diabetes prevalence was no longer increased in women.