Diabetes onset at an earlier age and high HbA1c levels as risk factors of diabetic retinopathy

AIM: To assess the effect of age at diabetes onset and uncontrollable high HbA1c levels on the development of diabetic retinopathy (DR) among Chinese type 2 diabetes mellitus (DM) patients. METHODS: This was a cross-sectional survey of diabetic patients in Subei district, China. Data covering physical measurements, fasting blood-glucose (FBG), glycosylated hemoglobin (HbA1c), blood lipid, urinary albumin/creatinine ratio (UACR), ocular fundus examination, and diabetes treatment records were collected. An independent sample t-test were used to analyze differences. A Logistic regression analysis was applied to study the independent risk factors of DR. RESULTS: A total of 1282 patients with type 2 DM were enrolled, and 191 cases had DR (14.9%). The age at diabetes onset, education level, alcohol consumption, HbA1c level, UACR level, and hypoglycemic drugs were independent influencing factors for DR. The older the onset of diabetes, the less likely to develop DR (OR: 0.958, 95%CI: 0.942-0.975, P=0.000). Patients were then divided in terms of age at diabetes onset as follows: <50y, 50-59y, 60-69y, and >= 70y. Compared with diabetes onset age <50y, 5059y (OR: 0.463, 95%CI: 0.306-0.699, P=0.000), 60-69y (OR: 0.329, 95%CI: 0.203-0.535, P=0.000) and >= 70y (OR: 0.232, 95%CI; 0.094-0.577, P=0.002) were at a lower risk of DR. The prevalence of DR was highest in patients with diabetes onset age <50y (29.5%, P<0.05). The HbA1c level (8.67 +/- 1.97)% and proportion of insulin injection (52.5%) in patients with diabetes onset <40y were higher than in patients with older diabetes onset age (P<0.05). CONCLUSION: Diabetes onset at an earlier age and uncontrollable high HbA1c level could be independent risk factors for DR.