Impact of Age of Onset, Puberty, and Glycemic Control Followed From Diagnosis on Incidence of Retinopathy in Type 1 Diabetes: The VISS Study.

Abstract

To evaluate sex, age at diabetes onset, puberty, and HbA_1c, with subjects followed from diabetes diagnosis and during different time periods, as risk factors for developing diabetic simplex and proliferative retinopathy. In a population-based observational study, HbA_1c for 451 patients diagnosed with diabetes before 35 years of age during 1983-1987 in southeast Sweden was followed for up to 18-24 years from diagnosis. Long-term mean weighted HbA_1c (wHbA_1c) was calculated. Retinopathy was evaluated by fundus photography and analyzed in relation to wHbA_1c levels. Lower wHbA_1c, diabetes onset ≤5 years of age, and diabetes onset before puberty, but not sex, were associated with longer time to appearance of simplex retinopathy. Proliferative retinopathy was associated only with wHbA_1c. The time to first appearance of any retinopathy decreased with increasing wHbA_1c. Lower wHbA_1c after ≤5 years' diabetes duration was associated with later onset of simplex retinopathy but not proliferative retinopathy. With time, most patients developed simplex retinopathy, except for those of the category wHbA_1c ≤50 mmol/mol (6.7%), for which 20 of 36 patients were without any retinopathy at the end of the follow-up in contrast to none of 49 with wHbA_1c >80 mmol/mol (9.5%). Onset at ≤5 years of age and lower wHbA_1c the first 5 years after diagnosis are associated with longer duration before development of simplex retinopathy. There is a strong positive association between long-term mean HbA_1c measured from diagnosis and up to 20 years and appearance of both simplex and proliferative retinopathy.