Prevalence of Diabetes in the United States: A Glimmer of Hope?

Obesity is a major risk factor for type 2 diabetes. The prevalence of obesity in US adults, defined as a body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) of 30 or greater, changed little between 1960 and 1980 (from 13% in 1960 to 15% in 1980). Subsequently, between 1980 and 2000, the prevalence of obesity in the United States doubled from 15% to 31%.1 Since then, there has been relatively little change in the prevalence of obesity among infants and toddlers, children and adolescents, or adults. Nevertheless, the prevalence of obesity is high with 8% of infants and toddlers, 17% of those aged 2 to 19 years, and 35% of US adults aged 20 years or older estimated to be obese.2,3 An earlier study of trends in diagnosed diabetes among US adults demonstrated stable incidence and prevalence rates between 1980 and 1990 and sharp increases in both incidence and prevalence each year between 1990 and 2008, but a leveling off of diabetes prevalence and a possible decrease in diabetes incidence between 2008 and 2012.4 In this issue of JAMA, Menke and colleagues5 analyzed data from the National Health and Nutrition Examination Survey (NHANES) to estimate the prevalence of total, diagnosed, and undiagnosed diabetes in US adults in 2011-2012 and to update national trends between 1988 and 2012. The authors defined diagnosed diabetes as self-report of a previous diagnosis of diabetes. Depending on the availability of data, they used 2 definitions for undiagnosed diabetes: (1) a hemoglobin A1c level of 6.5% or greater, a fasting plasma glucose (FPG) level of 126 mg/dL or greater, or a 2-hour plasma glucose (2 hours after a 75 g oral glucose load) level of 200 mg/dL or greater or (2) a hemoglobin A1c level of 6.5% or greater or an FPG level of 126 mg/dL or greater. In both instances, total diabetes was defined as the sum of the cases of diagnosed and undiagnosed diabetes. In 2011-2012, using the hemoglobin A1c, FPG, or 2-hour plasma glucose diabetes definition, the unadjusted prevalence was 14.3% for total diabetes, 9.1% for diagnosed diabetes, and 5.2% for undiagnosed diabetes. The prevalence of total diabetes was higher in older age groups but similar among men and women. Compared with non-Hispanic white participants in whom the age-standardized prevalence of total diabetes was 11.3%, the prevalence of total diabetes was higher in non-Hispanic black (21.8%) and Hispanic (22.6%) participants and marginally higher in nonHispanic Asian (20.6%) participants. The percentage of people with diabetes who were undiagnosed was higher among non-Hispanic Asian (50.9%) and Hispanic participants (49.0%) than among non-Hispanic black (36.8%) and non-Hispanic white (32.3%) participants. Using the hemoglobin A1c or FPG diabetes definition, the age-standardized prevalence of total diabetes increased from 9.8% in 1988-1994 to 12.5% in 2007-2008, but remained at approximately 12% between 2008 and 2012. The increase in diabetes prevalence between 1988 and 2012 was due to an increase in diagnosed diabetes. Indeed, the age-standardized percentage of total diabetes that was undiagnosed decreased from 40.3% in 1988-1994 to 31.0% in 2011-2012 in the entire US population. The percentage of total diabetes that was undiagnosed did not decrease significantly in people aged 20 to 44 years (40% in 1988 and 40% in 2012). These findings suggest that the recommendations issued by the US Surgeon General6 and the Institute of Medicine,7 the implementation of food, nutrition, agricultural, and physical activity policies and regulations by federal, state, and local governments,8 and the focus on individual behavioral change related to diet and physical activity by the US Centers for Disease Control and Prevention9 (CDC) have Related article page 1021 Editorial Opinion