Prevalence of and Trends in Diabetes Among Adults in the United States, 1988-2012

Importance: Previous studies have shown increasing prevalence of diabetes in the United States. New US data are available to estimate prevalence of and trends in diabetes.

Objective: To estimate the recent prevalence and update US trends in total diabetes, diagnosed diabetes, and undiagnosed diabetes using National Health and Nutrition Examination Survey (NHANES) data.

Design, Setting, And Participants: Cross-sectional surveys conducted between 1988-1994 and 1999-2012 of nationally representative samples of the civilian, noninstitutionalized US population; 2781 adults from 2011-2012 were used to estimate recent prevalence and an additional 23,634 adults from 1988-2010 were used to estimate trends.

Main Outcomes And Measures: The prevalence of diabetes was defined using a previous diagnosis of diabetes or, if diabetes was not previously diagnosed, by (1) a hemoglobin A1c level of 6.5% or greater or a fasting plasma glucose (FPG) level of 126 mg/dL or greater (hemoglobin A1c or FPG definition) or (2) additionally including 2-hour plasma glucose (2-hour PG) level of 200 mg/dL or greater (hemoglobin A1c, FPG, or 2-hour PG definition). Prediabetes was defined as a hemoglobin A1c level of 5.7% to 6.4%, an FPG level of 100 mg/dL to 125 mg/dL, or a 2-hour PG level of 140 mg/dL to 199 mg/dL.

Results: In the overall 2011-2012 population, the unadjusted prevalence (using the hemoglobin A1c, FPG, or 2-hour PG definitions for diabetes and prediabetes) was 14.3% (95% CI, 12.2%-16.8%) for total diabetes, 9.1% (95% CI, 7.8%-10.6%) for diagnosed diabetes, 5.2% (95% CI, 4.0%-6.9%) for undiagnosed diabetes, and 38.0% (95% CI, 34.7%-41.3%) for prediabetes; among those with diabetes, 36.4% (95% CI, 30.5%-42.7%) were undiagnosed. The unadjusted prevalence of total diabetes (using the hemoglobin A1c or FPG definition) was 12.3% (95% CI, 10.8%-14.1%); among those with diabetes, 25.2% (95% CI, 21.1%-29.8%) were undiagnosed. Compared with non-Hispanic white participants (11.3% [95% CI, 9.0%-14.1%]), the age-standardized prevalence of total diabetes (using the hemoglobin A1c, FPG, or 2-hour PG definition) was higher among non-Hispanic black participants (21.8% [95% CI, 17.7%-26.7%]; P < .001), non-Hispanic Asian participants (20.6% [95% CI, 15.0%-27.6%]; P = .007), and Hispanic participants (22.6% [95% CI, 18.4%-27.5%]; P < .001). The age-standardized percentage of cases that were undiagnosed was higher among non-Hispanic Asian participants (50.9% [95% CI, 38.3%-63.4%]; P = .004) and Hispanic participants (49.0% [95% CI, 40.8%-57.2%]; P = .02) than all other racial/ethnic groups. The age-standardized prevalence of total diabetes (using the hemoglobin A1c or FPG definition) increased from 9.8% (95% CI, 8.9%-10.6%) in 1988-1994 to 10.8% (95% CI, 9.5%-12.0%) in 2001-2002 to 12.4% (95% CI, 10.8%-14.2%) in 2011-2012 (P < .001 for trend) and increased significantly in every age group, in both sexes, in every racial/ethnic group, by all education levels, and in all poverty income ratio tertiles.

Conclusions And Relevance: In 2011-2012, the estimated prevalence of diabetes was 12% to 14% among US adults, depending on the criteria used, with a higher prevalence among participants who were non-Hispanic black, non-Hispanic Asian, and Hispanic. Between 1988-1994 and 2011-2012, the prevalence of diabetes increased in the overall population and in all subgroups evaluated.