Trends and racial/ethnic differences in age at diagnosis of adult-onset type 1 and type 2 diabetes in the United States, 2016-2022.

Introduction: Age at diagnosis of diabetes is important for informing public health planning and treatment strategies. This study aimed to estimate trends and racial/ethnic differences in age at diagnosis of adult-onset diabetes by type in the United States.

Methods: This serial nationwide cross-sectional study used data from the National Health Interview Survey in 2016-2022. Adults aged ≥18 years with self-reported age at diagnosis of adult-onset type 1 diabetes (T1D) or type 2 diabetes (T2D) were included. Trends in mean age at diagnosis of T1D and T2D and in proportions of people with T1D or T2D diagnosed at different ages were assessed by linear and logistic regressions. Racial/ethnic differences in mean age at diagnosis of T1D and T2D were determined.

Results: Included were 1224 T1D cases and 14,221 T2D cases. From 2016 to 2022, the mean age at diagnosis of T2D increased by 0.18 years annually (95% CI, 0.05-0.30 years, P =0.005), but no significant trend was observed for T1D. The proportion of T2D cases with diagnosis age ≥60 years increased by 3.17% and with diagnosis age in 18-29 years decreased by 5.62% annually (P ≤0.01). On average, Hispanic individuals had T1D diagnosed 3.2 years older and minority groups had T2D diagnosed 2.0-6.1 years younger than non-Hispanic White individuals (P ≤0.02).

Conclusions: Among US adults, the mean age at diagnosis of adult-onset T1D remained stable and of adult-onset T2D increased significantly from 2016 to 2022. Substantial and opposite differences in mean diagnosis age of T1D and T2D by race/ethnicity were identified.