Prevalence of retinopathy differs with age at onset of diabetes in a population of patients with Type 1 diabetes.

Abstract

The VISS study (Vascular complications in South-east Sweden) investigates prevalence and incidence of vascular complications in a population with Type 1 diabetes, from a well-defined geographical area and followed from diagnosis with HbA1c measurement. The study population comprised all 440 patients with Type 1 diabetes onset before the age of 36 years, onset during 1983-1987, and at the time of onset living within the counties of Jönköping, Kalmar or Ostergötland. Retinopathy was examined with fundus photography 1994-1995, and classified according to a modified Airlie House protocol. Fundus photographs from 390 patients were evaluated. In 277 (71%) patients no retinopathy was seen. The prevalence of retinopathy increased from 11% among patients < 5 years old at diabetes onset, to 48% among those 15-19 years old at diabetes onset, and then decreased to 30% for patients 30-35 years old at diabetes onset (P for chi2 for linear trend for all ages 0.017, for age at onset 0-19 years P = 0.0003), without corresponding differences in duration or HbA1c between patients with different onset age. Patients with HbA1c in the highest quartile (> 8.3% HbA1c) had a relative risk of 2.4 (95% confidence interval (CI) 1.7-3.2) of having any retinopathy compared with patients with lower HbA1c, and a relative risk of 7.1 (95% CI 3.0-16.7) of having other forms of retinopathy than microaneurysms. In patients with diabetes duration of 6-13 years, the prevalence of retinopathy is clearly related to glycaemic control. Furthermore, the risk of retinopathy varies with different age at onset, independently of differences in duration or glycaemic control.