Nonlinear relationship between systolic blood pressure and diabetic retinopathy in type 2 diabetic patients in southern China: a single-center observational study

Abstract

AbstractBackgroundBlood pressure (BP) control has been shown in clinical trials to reduce the risk of diabetic retinopathy (DR). To some extent, systolic blood pressure (SBP) has been shown to have a positive correlation with DR. However, there are no studies that have standardized SBP thresholds for DR prevention. Our goal was to use threshold analysis to further investigate the relationship between SBP and DR, identifying safe levels of SBP that contribute to DR preventionMethodsWe analyzed data from a cross-sectional study (December 2017-November 2018, n = 426, mean age 59.15±13.68) of patients with type 2 diabetes mellitus in the endocrinology department of Guangdong Provincial People’s Hospital, which is publicly available in the Dryad database. DR severity was assessed by retinal photographs. The International Clinical Diabetic Retinopathy and Diabetic Macular Edema Disease Severity Scale was used to classify DR severity and divide it into two groups: with DR and without DR. SBP was analyzed as a continuous variable. Multivariate logistic regression models, smoothed curve fitting, threshold analysis, and interaction tests were used to assess the relationship between SBP and DR.ResultsPrevalence of DR in the study population was 39.20%. After adjusting for age, sex, DM duration, HbA1c, BUN, HDL, LDL, TRIG, CHOL, TP, DBP, PP, eGFR, and CKD stage, the association between SBP and DR appears as a threshold effect, with a inflection point of 132 mm Hg. The risk of DR did not change significantly when SBP ≤132 mm Hg (OR: 0.86; 95% CI: 0.63 to 1.17, p=0.3400). When SBP ≥132 mm Hg, each 10 mm Hg increase in SBP raise the risk of developing DR by 28% (OR:1.28; 95% CI:1.07 to 1.54, P=0.0081). In addition, a stronger association of SBP with DR in patients with TP≤60g/L (OR=1.58, 95% CI: 1.19-2.08, P=0.001) compared to those with TP>60g/L (OR=1.15, 95% CI: 1.03, 1.27, P=0.012) was discovered, with a P value for interaction=0.023.ConclusionIn Chinese patients with type 2 diabetes, SBP was significantly associated with DR when SBP ≥132 mm Hg. Further longitudinal studies are needed to confirm our findings, especially in patients with TP≤60g/L.