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.

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.