Prior long term glycaemic control and insulin therapy in insulin-dependent diabetic adolescents with microalbuminuria

Adolescence seems to be a period of increased risk for the initiation of diabetic renal disease in insulin-dependent diabetic children. Poor glycaemic control is a risk factor for diabetic nephropathy. We have therefore evaluated prior long-term glycaemic control in 23 diabetic adolescents with microalbuminuria (albumin excretion rate (AER) 20-200 micrograms/min, median 39.0 micrograms/min) and in 23 matched diabetic controls with AER less than 20 micrograms/min (median 9.3 micrograms/min). Glycaemic control was assessed by mean HbA1 and clinic blood glucose levels over a period ranging from 12 to 84 months (median 48 months). Mean HbA1 was 13.6 +/- 2.0% in the microalbuminuric subjects, compared to 11.5 +/- 2.2% in the controls (P less than 0.002); mean blood glucose levels were 13.5 +/- 3.0 and 11.4 +/- 3.0 mmol/l, respectively (P less than 0.02). There appeared to be a 'threshold effect' (mean HbA1 greater than 12.0%), above which the development of microalbuminuria was more likely. More patients with microalbuminuria than controls had been treated with a single rather than twice-daily insulin injections (P less than 0.001), and glycaemic control was significantly worse in patients treated with one injection. We conclude that poor long term glycaemic control is a risk factor for microalbuminuria, and that improving control during childhood is likely to reduce the prevalence of later microalbuminuria. Two insulin injections, of combined intermediate and short-acting preparations, are more likely to provide better control than a single daily insulin dose.