BACKGROUND. Type 2 diabetes mellitus (T2DM) is a complex, multifactorial disease that is a consequence of the progressive insulin secretory defect and peripheral insulin resistance. In the course of disease the long-lasting hyperglycaemia leads to the chronic complications. Diabetic retinopathy is a highly specific microvascular complication of this disease. It is the most frequent cause of new cases of blindness among adults. The aim of the study was to define the prevalence of diabetic retinopathy in patients with T2DM from a Polish population and to analyze the clinical features associated with this complication in the examined group.
MATERIAL AND METHODS. The study group consisted of 359 T2DM patients with age of diagnosis above 35 years. The diagnosis of DR was based on the ophthalmologic examination and ophthalmoscopy after the dilation of pupils. The photographic documentation was done. Potentially important clinical covariables such as gender, age, duration of diabetes, BMI, smoking status, the presence of hypertension and some biochemical factors were also measured.
RESULTS. We examined 359 subjects, all European Caucasians, residents of Poland with T2DM. The examined group consisted of 198 (55.2%) female and 161 (44.8%) male T2DM patients (mean age at examination: 60.8 ± 9.4 years, age at T2DM diagnosis: 49.7 ± 9.2, T2DM duration: 11.2 ± 7.0 years, body mass index: 31.3 ± 7.4 kg/m², HbA_1c: 7.5 ± 1.5 %). Diabetic retinopathy of different stages was detected in one third of the examined diabetic group (33.7%). Proliferative retinopathy was diagnosed in 8 subjects, what constituted 2.2% of the entire T2DM group. The morbidity differed in the sub-groups defined based on the disease duration. Among the patients with diabetes duration below 10 years retinopathy was diagnosed in 18.3% (n = 33) patients, while in the sub-group with diabetes duration between 10 and 20 years retinopathy was present in 43.7% (n = 52) of T2DM individuals. In the group of patients with the longest history of diabetes (above 20 years), retinopathy was observed in 62.5% (n = 35) subjects. The multivariate analysis revealed that significant predictors of diabetic retinopathy were: age at diagnosis of diabetes (p = 0.01; OR: 0.96; 95% CI: 0.92-0.99), duration of diabetes (p = 0.003; OR: 1.06; 95% CI: 1.02-1.10), HbA_1c level (p = 0.001; OR: 1.35; 95% CI 1.13-1.63), never-smoking status (p = 0.001; OR: 0.41; 95% CI 0.23-0.71), and urea serum level (p = 0.009; OR 1.19; 95% CI: 1.05-1.36).
CONCLUSIONS. The prevalence of diabetic retinopathy was 33.7% in examined populations. We were able to confirm the role of some clinical risk factors in the pathogenesis of DR such as age at diagnosis of diabetes, duration of the disease, HbA_1c level, never smoking status, urea serum level.