The Prevalence of Diabetic Retinopathy in the 21st Century: New Insights From a Portuguese Center

Introduction Diabetic retinopathy (DR) is a leading cause of vision loss among working-age adults; yet, robust prevalence data remain scarce. In this study, we aimed to determine the prevalence of DR and identify its main associated risk factors in adults with type 2 diabetes mellitus (T2DM) monitored at a family health unit in northern Portugal Methods This retrospective study evaluated all patients at a family health unit diagnosed with T2DM between 2002 and 2013. Electronic records were screened for retinal evaluations, <i>via</i> the national screening or opportunistic exams. All patients who had undergone a retinal exam 10 years after their diabetes mellitus (DM) diagnosis were included. Baseline data - including gender, age, diabetes duration, glycated hemoglobin, smoking history, and hypertension - were collected, along with DR presence and its classification. The main outcomes were prevalence, type, risk factors, and complications of DR. Results Between 2002 and 2013, 355 patients were diagnosed with T2DM at this family health unit. Of these, 64 were excluded due to the absence of a retinal evaluation at the 10-year follow-up. Among the 294 included patients, 152 were female, with a mean age at diagnosis of 71.1 ±12.1 years. Most (257/294) were evaluated through the national screening program, with the remaining being evaluated through an opportunistic appointment. Overall, 18 patients were diagnosed with diabetic retinopathy (point prevalence: 6.12%). Of these, 14 were male (78%), four developed macular oedema, eight underwent LASER treatment, and one required <i>pars plana</i> vitrectomy for proliferative DR. Patients with DR had worse glycemic control (mean glycated hemoglobin: 7.67 ±1.07 vs. 6.61 ±0.74 in those without retinopathy, <i>p</i><0.001) and a higher need for insulin (33% vs. 8.3%, <i>p</i>=0.002). Hypertension and smoking habits did not significantly differ between groups. Conclusions DR prevalence and risk factors vary in the literature due to differences in studied populations and methodologies. Reported prevalence ranges from 20 to 35% over 5-10 years and is closely associated with poor glycemic control and the need for insulin therapy. The significantly lower rate observed in our study may reflect earlier diagnosis and improved access to treatment, highlighting the importance of systematic screening and proper glycemic control in patients with T2DM. Early identification of these patients can provide tailored follow-up strategies, guide timely therapeutic interventions, and ultimately help prevent vision-threatening complications. Furthermore, our results may serve as a foundation for further research on the current impact of T2DM on ophthalmic health services. Larger, multicentric studies are needed to provide a more comprehensive and up-to-date picture of DR within today's healthcare systems.