Trends in Diagnosed Diabetes, Undiagnosed Diabetes, and Prediabetes

Study Questions:

What are the prevalence and trends in total, diagnosed, and undiagnosed diabetes and prediabetes in the United States?


As part of the National Health and Nutrition Examination Survey (NHANES), cross-sectional data were collected between 1988-1994, and continuously in 2-year cycles since 1999. Data from 2011-2012 were used to estimate recent trends in diabetes prevalence. The authors used definitions of undiagnosed and total diabetes. First undiagnosed diabetes was defined as any participant who had a glycated hemoglobin of ≥6.5%, a fasting plasma glucose (FPG) level of ≥126 mg/dl, or a 2-hour postprandial glucose (PG) level of ≥200 mg/dl. Total diabetes was any participant who had either diagnosed diabetes or undiagnosed diabetes defined by glycated hemoglobin, FPG, or 2-hour PG. The authors also defined prediabetes. Cross-sectional data were used to determine the prevalence of total diabetes, previously diagnosed diabetes, and undiagnosed diabetes, as well as the percentage of total diabetes that was undiagnosed and the prevalence of prediabetes in the overall population, stratified by age, sex, and race/ethnicity.


The unweighted analytic sample was 2,781 for NHANES 2011-2012. In the overall population, the unadjusted prevalence was 14.3% (95% confidence interval [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%). Compared with non-Hispanic white participants (11.3%; 95% CI, 9.0%-14.1%), the age-standardized prevalence of diabetes was higher in non-Hispanic black participants (21.8%; 95% CI, 17.7%-26.7%; p < 0.001), non-Hispanic Asian participants (20.6%; 95% CI, 15.0%-27.6%; p = 0.007), and Hispanic participants (22.6%; 95% CI, 18.4%-27.5%; p < 0.001). The age-standardized percentage of total diabetes that was undiagnosed decreased from 40.3% (95% CI, 34.9%-45.7%) in 1988-1994 to 31.0% (95% CI, 25.2%-37.4%) in 2011-2012 (p < 0.001).


The weighted prevalence of diabetes was high (12%-14% in the overall population and >10% in all sex and racial/ethnic groups). More than one in three people with diabetes were previously undiagnosed. Almost 50% of the population was estimated to have either diabetes or prediabetes.


The authors provide useful insight into the prevalence of and trends in diabetes among adults in the United States. Between 1988-1994 and 2011-2012, the prevalence of diabetes increased in the overall population and in all subgroups evaluated. The prevalence of prediabetes is a continued call to action, as 49% to 52% of the population was estimated to have either diabetes or prediabetes. As the authors posit, the rapid increase in diagnosed diabetes, along with no change in undiagnosed diabetes, may suggest improved detection. It is also reassuring to note that while there was a linear increase between 1988-1994 and 2011-2012, prevalence estimates changed little between 2007-2008 and 2011-2012. This plateauing of diabetes prevalence is consistent with obesity trends, which have also leveled off.

Clinical Topics: Diabetes and Cardiometabolic Disease, Prevention

Keywords: Diabetes Mellitus, Hemoglobin A, Glycosylated, Glucose, Metabolic Syndrome X, Obesity, Prediabetic State, Prevalence, Primary Prevention

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