Long-term National Trends in the Prevalence of Type 2 Diabetes Mellitus and the Association with Social Determinants of Health in Korean Adults, 2007-2024.

Abstract

Background: Type 2 diabetes mellitus (T2DM) is linked to social determinants of health (SDOH); however, long-term trends in its prevalence and the association with SDOH remain unclear. Thus, we investigated national trends in T2DM prevalence and the cumulative burden of SDOH.

Methods: We analyzed data from the Korea National Health and Nutrition Examination Survey (2007-2024), including adults aged ≥ 19 years. T2DM was defined by physician diagnosis, use of anti-diabetic medication, fasting glucose ≥ 126 mg/dL, or hemoglobin A1c ≥ 6.5%. SDOH was assessed across seven key domains-education level, marital status, household income, food security, type of health insurance, employment status, and home ownership- and classified into low- (≤ 2) and high-burden (> 2) groups; the cumulative score was also analyzed as ordinal and continuous variables to evaluate dose-response relationships. Trends were examined using weighted linear regression, and adjusted odds ratios ( aORs) were estimated using multivariable logistic regression across pre- (2007-2019), intra- (2020-2022), and preliminary post-pandemic (2023-2024) periods. Age-standardized estimates and sensitivity analyses, including inverse probability weighting and mediation analysis, were performed to ensure robustness.

Results: A total of 85,695 adults (males; 35,392, 41.30%) were included. The prevalence of T2DM showed increasing trend (8.55%, 95% CI: 7.96% to 9.13% in 2007-2009; 11.66%, 95% CI: 11.11% to 12.22% in 2016-2019), and a surge was observed at the onset of the pandemic in 2020, peaking at 13.66% (95% CI: 12.24% to 15.07%) in 2021 before rebounding to 14.19% (12.99%-15.39%) in 2024. High cumulative SDOH was associated with T2DM ( aOR = 1.33, 95% CI: 1.25 to 1.41), showing a clear dose-response relationship where the risk progressively escalated with higher SDOH scores (score ≥ 6: 1.79 [1.58 to 2.04]). Among individual components, lack of private health insurance showed the strongest association ( aOR = 1.30, 95% CI: 1.22 to 1.39). Other major risk factors included established demographic and clinical predictors such as older age, male, and obesity.

Conclusions: T2DM prevalence has increased over time, and a high cumulative burden of SDOH remains consistently associated with this prevalence, highlighting the need for equity-focused public health strategies.