Systolic Blood Pressure Is An Independent Risk Factor For Diabetic Retinopathy In Both Hypertensive And Normotensive Patients

Abstract

Introduction: Treatments with targets of systolic blood pressure (BP) <140 mmHg reduce the onset, or decrease the progression of diabetic retinopathy (DR) - a most common microvascular complication in type 2 diabetic patients with established hypertension. However, the debate on further intensive vs. standard BP control targets in limiting the onset and progression of diabetic microvascular complications remains to be an area of controversy. We aimed to explore whether the extent to which systolic BP levels were associated with the presence of DR in type 2 diabetic patients with normal BP were similar to that in patients with coexisting hypertension. Hypothesis: We assessed the hypothesis that systolic BP levels were not associated with DR in normotensive patients. Methods: This was a baseline analysis of a cohort of adult Chinese patients diagnosed with type 2 diabetes who attended ophthalmoscopic exam with primary care referral in the context of a Specialist-Generalist Working Alliance in Guangzhou, China. A hospital-based, standardised investigation included a dilated, comprehensive eye examination, a measurement of BP values and anthropometric parameters, and a clinical laboratory test for haemoglobin A1c and lipid profiles. A binary logistic regression analysis was conducted to examine patient-level risk factors associated with DR. Results: The mean age of all study participants (N=2,510) was 64.8 years, and more than half were females. More than one in three patients (40.4%) were normotensive. The average duration of diabetes was 8.6 years, and one in five patients were clinically diagnosed with DR. A higher systolic BP level was significantly associated with DR (adjusted odds ratio [aOR]=1.019, 95%CI: 1.012-1.027; p<0.001 for hypertensives, and aOR=1.020, 95%CI: 1.005-1.036; p=0.009 for normotensives), after adjusting for diabetes duration, sex, lifestyle behaviours, and HbA1c levels. Conclusions: In conclusion, we found that increased systolic BP level was an independent, significant risk factor associated with DR in both hypertensive and normotensive diabetic patients. Physicians, patients and caregivers are recommended to maintain regular monitoring of BP in all diabetic patients irrespective of the coexistence of hypertension.