Associations between blood pressure levels and diabetic retinopathy in patients with diabetes mellitus: A population-based study.

Purpose: To evaluate the associations of blood pressure levels with diabetic retinopathy (DR), proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME) in patients with diabetes mellitus. Design: A cross-sectional, population-based study. Subjects: A total of 152,844 patients with diabetes from 90 major cities in 19 provincial regions of mainland China during 2018-2021 were finally recruited. Methods: Blood pressure was graded into 5 levels: normal (without hypertension and <120/80 mmHg), normal high (without hypertension and ≥120/80 mmHg), HT-intensive (hypertension and <120/80 mmHg), HT-moderate (hypertension and blood pressure between 120/80 mmHg and 140/90 mmHg) and HT-high (hypertension and ≥140/90 mmHg). Logistic regression was employed to verify the associations of hypertension and blood pressure levels with DR, PDR and DME. The impacts of blood pressure levels on the outcomes were qualified with nomogram models. Main outcome measures: The main outcome was DR. Results: There were 16,685 (10.92%) participants having DR, 2841 (1.86%) having PDR, and 1566 (1.02%) having DME. There were 8126 (5.32%) patients without hypertension and 1350 (0.88%) patients with hypertension having blood pressure <120/80 mmHg. When compared to the normal group with covariates adjusted, an increased prevalence of DR was observed in normal high (adjusted odds ratio [OR] = 1.114, 95% confidence interval [CI] = 1.033-1.202), HT-moderate (adjusted OR = 1.163, 95% CI = 1.065-1.271), and HT-high (adjusted OR = 1.203, 95% CI = 1.114-1.300). Conclusions: There were associations between hypertension and DR, PDR, and DME in the diabetic population. Increased prevalence of DR was found with blood pressure >120/80 mmHg in both patients with and without hypertension. A nomogram was developed for DR prediction based on blood pressure levels.