Age at diagnosis, glycaemic control and the development of retinopathy in a population-based cohort of Type 1 diabetic subjects in Canterbury, New Zealand

The aim was to determine the relationship between age at diagnosis, glycaemic control and the development of retinopothy in a population-based cohort of Type I diabetic subjects. At 1 January 1984, there were 286 individuals with Type 1 diabetes (and age of onset < 20 years) on the Canterbury, New Zealand population register who had at least 2 prospective HbA(1c) readings (from 1 January 1984). Of these, 107 already had retinopathy. Of the 179 subjects without retinopathy at baseline 63 developed retinopathy during follow-up. After controlling for duration of diabetes: tin the whole group), age at diagnosis was found to be a significant predictor of HbA(1c) level (P = 0.001). with higher (mean <plus/minus> SD) baseline HbA(1c) in the 10-14 age group (7.95 +/- 2.14%,), compared with (7.62 +/- 1.77%) in the < 10 year group and (7.39 <plus/minus> 12.57%) in the > 14 year group. The major predictors of retinopathy tin those without retinopathy at baseline), however were duration of diabetes (mean time to development of It retinopathy decreases by 14% (95% Cl 10 17%) for each year), baseline HbA(ac) (for each unit increase, mean lime to development of retinopathy decreased by 23%(95%Cl 13-32%) and HbA(1c) slope (average annual change). Peri-pubertal age at diagnosis(10-14 years) did not influence the lime to onset of retinopathy over and above that attributed to duration of diabetes and glycaemic control. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.