The North Jutland County Diabetic Retinopathy Study (NCDRS). Population characteristics.

Abstract Purpose: Several population based studies have reported blood glucose levels and blood pressure to be risk factors for the development of proliferativ retinopathy and diabetic maculopathy. Despite their importance, these studies were initiated more than two decades ago and may therefore reflect the treatment and population composition of a previous era. Studies of the present diabetic population are therefore in demand. Methods: The present cross–section study included 656 type 1 and 328 type 2 diabetic subjects undergoing diabetic retinopathy screening. Crude prevalence rates for proliferative diabetic retinopathy, maculopathy, several specific lesions and non–ophthalmic findings were assessed together with their association to a simplified and internationally approved retinal grading. Results: The crude prevalence of proliferative retinopathy was found to be 5.6 % and 0.9 % for type 1 and type 2 diabetes. Equivalent prevalence rates for diabetic maculopathy were 7.9 % and 12.8 %, respectively. The most frequently occuring retinal manifestations (microaneurysms, bleedings, hard exudates and soft exudates) were found to increase in number up to retinopathy level 3 followed by decrease. The prevalence of diabetic maculopathy also increased up to retinopathy level 3 followed by decrease. Less frequently occuring retinal manifestations occured at frequences in the range of 0.0–2.5 % and were only observed at retinopathy level 3 and 4. Conclusions: The prevalence of proliferative retinopathy is lower than that of previous studies, possibly due to improved blood glucose regulation, while the prevalence of diabetic maculopathy is similar or possibly slightly higher. This could suggest that other and more important risk factors than blood glucose levels dominate the development and progression of diabetic maculopathy.