Lowering Blood Pressure Reduces Retinopathy Risk in Patients With Diabetes

For patients with diabetes, lowering blood pressure can reduce the risk of developing diabetic retinopathy (DR), according to a study published in Heliyon. Patients with hypertension have an 8.1%, 38.1%, and 23.5% increased risk of DR, proliferative diabetic retinopathy (PDR), and diabetic macular edema (DME), respectively, the report shows.

The Real-world Retinopathy Screening Project for Diabetic Population (RRSPD) study, guided by the National Clinical Research Center for Ophthalmic Diseases of China between December 2018 and November 2021, evaluated how lowering blood pressure levels affects DR, PDR, and DME in patients with diabetes mellitus.

A total of 152,844 participants with a diabetes duration of 4.71±5.07 years aged 64.02±10.43 years from 90 cities in 19 provincial regions of mainland China were included in the final analysis. Of these, 16,685 had DR, 2841 had PDR, and 1566 had DME. 

A total of 46.28% of patients had hypertension. Among them, only 5.32% of patients without hypertension and 0.88% with hypertension had a blood pressure lower than 120/80 mm Hg. Logistic regression analysis indicated that a history of hypertension increased the adjusted odds ratios for DR (adjusted OR=1.081; 95% CI, 1.045–1.117), PDR (adjusted OR=1.381; 95% CI, 1.280–1.491), and DME (adjusted OR=1.235; 95% CI, 1.115–1.367). 

Additionally, the prevalence of DR increased by 11.4% in normal high systolic blood pressure [SBP] ≥120 mmHg or diastolic blood pressure [DBP] ≥80 mmHg), 16.3% in hypertension-moderate (120 mmHg ≤ SBP <140 mmHg and 80 mmHg ≤ DBP <90 mmHg), and 20.3% in hypertension-high (SBP ≥140 mmHg or DBP ≥90 mmHg) blood pressure groups. An increased prevalence of PDR or DME was found in the hypertension-moderate group, but not the hypertension-intensive group. 

“This nationwide study confirmed the association between hypertension and DR, PDR, and DME in the diabetic population. We found that patients with and without hypertension benefited from a blood pressure <120/80 mmHg for reducing DR,” the researchers report. “For the sake of cardiovascular risks, the reduction is usually 10–20 mmHg, corresponding to a blood pressure target of 120–130/80–90 mmHg in diabetes. However, an appropriate blood pressure target to reduce DR in diabetes is still lacking.”

Study limitations include the possible underestimation of DR caused by using non-mydriatic one-field fundus images; unmeasured genetic, environmental, or behavioral factors; and the study’s cross-sectional nature.