Long-Term Patterns in Diabetes, Prediabetes, and Obesity in US Adults: Age-Adjusted Joinpoint Analyses of the National Health and Nutrition Examination Survey 1999-2023.

Objectives. I used nationally representative data from 1999 to 2023 in the United States to examine long-term trends and inflection points in diabetes, prediabetes, and obesity. Methods. I analyzed National Health and Nutrition Examination Survey 1999-2000 to 2021-2023 data. Diabetes and prediabetes were defined by hemoblogin A1c and obesity by anthropometrics. Survey-weighted models estimated age-adjusted prevalence; Joinpoint regression identified temporal inflection points, and multivariable models assessed sociodemographic associations. Results. Among 62 615 US adults, age-adjusted diabetes prevalence increased from 1999-2000 to 2021-2023 (annual percent change [APC] = 2.49%; P < .001), as did obesity (APC = 1.67%; P < .001). Prediabetes rose through 2009-2010 (APC = 8.61%; P < .001) before stabilizing. Adults aged 65 years or older had higher odds of diabetes (adjusted odds ratio [AOR] = 7.8) and prediabetes (AOR = 9.0) than those aged 18 to 44 years. Non-Hispanic Blacks had nearly 2-fold higher odds of diabetes and obesity than non-Hispanic Whites. Lower income and education were associated with higher odds of all outcomes. Uninsurance was associated with lower observed diabetes but similar prediabetes prevalence, consistent with underdiagnosis. Housing tenure was not independently associated with diabetes. Conclusions. Diabetes, prediabetes, and obesity increased over 2 decades. Persistent disparities underscore the need for equity-focused prevention. (Am J Public Health. Published online ahead of print September 17, 2026:e1-e11. https://doi.org/10.2105/AJPH.2026.308703).