Trends and disparities in diabetes and prediabetes among adults in the United States, 1999–2018

Objective: The aims of the study were to describe the up-to-date trend of total, diagnosed, and undiagnosed diabetes and prediabetes, assess their associated disparities among population subgroups, and examine their relationship with sociodemographic factors among adults in the United States. Study design: This was a cross-sectional study from a nationally representative sample of US adults (aged ≥20 years) who participated in the National Health and Nutrition Examination Survey. Methods: Diagnosed diabetes was defined as a self-reported previous diagnosis of diabetes by a physician or any other health professionals (other than during pregnancy). Undiagnosed diabetes was defined as elevated levels of fasting plasma glucose (≥126 mg/dL) or HbA_1c (≥6.5%). Total diabetes included those who had either diagnosed or undiagnosed diabetes. Prediabetes was defined as an HbA_1c level of 5.7%–6.4% or a fasting plasma glucose level of 100–125 mg/dL. All estimates were age standardized to the 2010 US census population for age groups 20–44, 45–64, and 65+ years. All analyses accounted for the complex survey design. Logistic regressions were used to conduct the analyses. Results: A total of 21,600 (mean, 47.2 years [SD, 14.7]) individuals were analyzed. From 1999 to 2018, the age-standardized prevalence increased significantly from 9.17% to 14.7% (difference, 5.52%; 95% confidence interval [CI], 2.69%–8.35%; P-trend <0.001) for total diabetes, increased from 6.15% to 11.0% (difference, 4.79%; 95% CI, 2.27%–7.32%; P-trend<0.001) for diagnosed diabetes and remained stable from 3.01% to 3.73% (difference, 0.72%; 95% CI, −0.47% to 1.91%; P-trend = 0.19) for undiagnosed diabetes. The age-standardized prevalence of prediabetes increased significantly from 29.5% to 48.3% (difference, 18.8%; 95% CI, 13.3%–24.4%; P-trend<0.001). Disparities persisted with higher prevalence among adults with obesity and populations that have been marginalized, including racial and ethnic minorities, low income, less educated Americans, and those living in food-insecure household. Conclusions: The prevalence of diabetes and prediabetes increased significantly from 1999 to 2018 among US adults. There are substantial and persistent disparities among racial and ethnic minorities, populations experiencing socio-economic disadvantages, and adults with obesity.