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

Objective: To evaluate sex, age at diabetes onset, puberty, and HbA, with subjects followed from diabetes diagnosis and during different time periods, as risk factors for developing diabetic simplex and proliferative retinopathy.

Research Design And Methods: In a population-based observational study, HbA 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 (wHbA) was calculated. Retinopathy was evaluated by fundus photography and analyzed in relation to wHbA levels.

Results: Lower wHbA, 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. The time to first appearance of any retinopathy decreased with increasing wHbA. Lower wHbA 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 ≤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 >80 mmol/mol (9.5%).

Conclusions: Onset at ≤5 years of age and lower wHbA 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 measured from diagnosis and up to 20 years and appearance of both simplex and proliferative retinopathy.