The WHO multinational study of vascular disease in diabetes: 3. Microvascular disease.

A preliminary comparison and analysis of microvascular disease was performed in 14 stratified samples of diabetic subjects. Microvascular disease was assessed by estimating visual disabilities, by standardized examination of the optic fundus by direct ophthalmoscopy, by estimating proteinuria, and by measuring the serum creatinine concentration. Visual impairment by questionnaire positive varied considerably between centers, probably due to cultural differences in interpretation of the questions. Physician-assessed visual disability also yielded considerable differences in frequency; however, the frequency differences were unrelated to those observed for macrovascular disease. Retinopathy--the sum of all components--was related to duration of diabetes in each participating center. The apparent frequency of proteinuria varied considerably between centers. In general, the frequency of retinopathy was related to the level of systolic blood pressure, but there was no systematic association with cigarette smoking.