Differential Associations of Social Determinants of Health with Diabetic Kidney Disease and Treatment Targets in Korean Adults with Diabetes

Background: Social determinants of health (SDOH) are linked to adverse diabetes outcomes internationally, but it remains unclear whether these associations are uniform or concentrated across major treatment targets in Korea's universal-coverage setting. Methods: We analyzed two Korea National Health and Nutrition Examination Survey cohorts (2021??024, n=3,129; 2011??014, n=2,602). A 4-item SDOH composite was derived from 14 candidate items; because the cohort×SDOH interaction was nonsignificant (P=0.36), the cohorts were pooled (n=5,731). Outcomes included diabetic kidney disease (DKD)-related laboratory abnormalities, defined using Kidney Disease: Improving Global Outcomes (KDIGO)-consistent single-measurement thresholds, severe hyperglycemia (glycosylated hemoglobin [HbA1c] ≥8%), uncontrolled blood pressure (≥140/85 mm Hg), and elevated low-density lipoprotein cholesterol (LDL-C; ≥100 mg/dL). Associations were analyzed using survey-weighted logistic regression adjusted for age, sex, body mass index, and cohort. Results: The composite showed a dose-response association with DKD-related laboratory abnormalities (15.9% [score 0] to 34.2% [score ??]; odds ratio [OR] per +1 item, 1.23; 95% confidence interval [CI], 1.14 to 1.33; P<0.001). It was associated with severe hyperglycemia (OR, 1.13; 95% CI, 1.03 to 1.23), but not uncontrolled blood pressure (OR, 0.95; 95% CI, 0.88 to 1.02) or elevated LDL-C (OR, 1.00; 95% CI, 0.94 to 1.08). The HbA1c association was threshold-dependent, emerging only at severe-hyperglycemia levels. This pattern persisted among actively treated patients. Sequential adjustment for HbA1c ≥8% and blood pressure attenuated the SDOH-DKD association by less than 1%. Conclusion: Cumulative social disadvantage was associated with DKD-related laboratory abnormalities and severe hyperglycemia, but not failure to meet blood pressure or lipid targets. These exploratory findings may inform future SDOH assessment in Korean diabetes care. Longitudinal registry-linked studies are needed to confirm chronicity and temporality.