Association between hematocrit and diabetic retinopathy in patients with type 2 diabetes mellitus: a cross-sectional study

This study aimed to examine the association between hematocrit (HCT) and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus. Cross-sectional data from 1,761 patients with type 2 diabetes mellitus who were treated at Longyan First Hospital between July 2022 and August 2025 were analyzed. Fundus status was assessed using standardized methods, and DR was independently evaluated by two ophthalmologists holding at least deputy chief physician titles in accordance with the International Clinical Diabetic Retinopathy Severity Scale. Fasting venous blood samples were collected in the morning, and HCT was measured using an automated blood cell analyzer. Associations between HCT and DR were examined using descriptive and univariate logistic regression analyses. In multivariable analyses adjusted for age, sex, BMI, and HbA1c, HCT categories were not significantly associated with DR (middle vs. low: OR = 0.76, 95% CI: 0.54–1.05, P = 0.10; high vs. low: OR = 0.95, 95% CI: 0.70–1.29, P = 0.74). ROC analysis showed limited discriminative performance of HCT for DR, with an AUC of 0.600, indicating insufficient value for clinical screening or risk stratification. In multivariable analyses adjusted for age, sex, BMI, and HbA1c, HCT categories were not significantly associated with DR. The previously observed unadjusted association was attenuated and became non-significant after covariate adjustment, suggesting that the univariate findings were largely explained by confounding factors. Further multicenter and longitudinal studies using prespecified and statistically stable multivariable models are warranted. Not applicable.