Clinical implications of systolic blood pressure for diabetic retinopathy across HbA1c levels in a Japanese population

This study evaluated the association between systolic blood pressure (SBP) and diabetic retinopathy (DR) across different glycemic levels in a Japanese population. We analyzed data from 1,049 residents aged ≥ 40 years with diabetes who underwent ophthalmic screening in Chikusei City. Participants were stratified into four groups by glycated hemoglobin (HbA1c) level (< 7% or ≥ 7%) and SBP (< 140 or ≥ 140 mmHg). Logistic regression was used to examine associations between SBP and prevalent DR within HbA1c strata. DR was present in 136 participants (13.0%), including 82 (7.8%) with mild-to-moderate nonproliferative DR (NPDR) and 54 (5.1%) with severe NPDR or proliferative DR (PDR). Among participants with lower HbA1c levels, higher SBP was significantly associated with greater odds of DR (odds ratio, 2.21; 95% confidence interval, 1.16–4.23). A similar association was observed among those with mild-to-moderate NPDR, but not among participants with higher HbA1c levels. SBP was not significantly associated with severe NPDR or PDR in any group. These findings suggest that elevated SBP may contribute to the development of early-stage DR even in individuals with well-controlled blood glucose levels, underscoring the importance of blood pressure management in DR prevention strategies.