Incidence of blindness in relation to diabetes. A population-based study

A reduction of diabetes-related blindness was declared a primary objective for Europe (St. Vincent Declaration). We collected data about incidence rates of blindness in the diabetic population compared with the nondiabetic population. Up to now, such data are scarce-even worldwide.

A complete list of newly registered blindness allowance recipients was drawn up in the district of Württemberg-Hohenzollern, Germany, between 1990 and 1993. From these data, we estimated age-specific and standardized incidence rates of blindness in the entire, the diabetic, and the nondiabetic population, as well as relative and attributable risks due to diabetes.

There were 2,714 people meeting the inclusion criteria; 1,823 (67.2%) were female and 781 (28.8%) had diabetes. In 318 subjects, diabetes was likely to be the only cause of blindness; in 192 subjects, it was one of several contributory causes. Age of women was 73.9 +/- 19.4 years (mean +/- SD) and of men 63.3 +/- 25.5 years. Results standardized to the (West) German population are as follows: incidence rates (per 100,000 person-years): total population: 13.5; diabetic population: 60.6; nondiabetic population: 11.6; relative risk: 5.2; attributable risk among exposed: 0.81; and population attributable risk: 0.14. The relative risks decreased considerably with increasing age. When the study is repeated to monitor the St. Vincent targets, a reduction in the incidence rate of blindness in the diabetic population by 17% will be detected with 95% power.

Great relative and attributable risks, especially in younger age-groups, indicate the need for increased attention to preventive measures for microvascular complications.