Determinants of microangiopathy in growth-onset diabetes. With special reference to retinopathy and glycaemic control.

In a quasi-experiment all diabetic children in a defined area were exposed either to an intense clinical treatment or served as a constructed control. The cohort of 146 diabetics was observed prospectively for at least 15 years as to diabetic control, mainly glycosuria, and cross-sectionally examined for microangiopathy on four occasions. Data on family background, social situation, smoking, blood pressure, biochemical status, anthropometry, HLA factors and mortality were also gathered. Throughout the analysis duration was considered and treated as a concomitant variable. Two different strategies have been followed in the analysis, one trying to predict microangiopathy at a fixed and predetermined duration, the other to study determinants of the pattern of microangiopathy occurrence over time. Multiple logistic regression and Cox analysis have been used to fit these strategies. The prevalence of microaneurysms or more advanced stages of retinopathy at 10 years duration was 30 per cent and within 20 years 81 per cent. About 52 per cent had haemorrhages after 20 years. Mild and severe nephropathy after 20 years have been contracted by 50 and 15 per cent respectively. No clear sex differences were seen. Variables significantly explaining retinopathy within 10 years were post-pubertal duration, blood pressure, place of medical supervision and the HLA/DR4 marker. The mean glycosuria was high during puberty irrespective of age at onset. The overall pattern of retinopathy occurrence seemed to be influenced by place of medical supervision, age at onset, blood pressure, family history of ischaemic heart disease and glycemic control. For the progression of retinopathy the role of factors reflecting medical supervision and control of diabetes seemed even greater. Even after accounting for degree of diabetic control the experimental group had a more favourable outcome, suggesting additional quality of care components. Mild nephropathy was less predictable from the above risk factors while previous findings of the important role of elevated blood pressure for severe nephropathy was confirmed. We estimate that half of retinopathy cases were preventable by the "experimental" care and conclude the near-normalization of glycaemia under routine conditions favourably influences the development of diabetic retinopathy.