Blindness in insulin-treated diabetic patients with age at onset less than 30 years.

The occurrence of blindness was evaluated in a population-based group of Danish patients with insulin-treated diabetes diagnosed before the age of 30 years (N = 727), identified by means of insulin prescriptions. The study comprised a retrospective cross-sectional investigation, a longitudinal observation during the subsequent approximately 8 years, and a cross-sectional ophthalmological examination of all patients still alive at the end of the 8 year observation period. Prevalence rates of registered blind at base line were 3.4 and 2.6% for men and women, respectively. The overall incidence rate for blindness was found to be approximately 1.0 per 100 person years. At the ophthalmological examination 88% of blind patients were registered by the Danish Society for the Blind. The cause of blindness in the majority of patients was proliferative retinopathy. Blindness was found to be a significant problem in insulin-dependent diabetes, with a 50-80 times higher risk of blindness than the background population.