Metabolic control and its variability are major risk factors for microalbuminuria in children with type 1 diabetes.

INTRODUCTION: To assess in a prospective study the course and the predictors of microalbuminuria in children and adolescents with type 1 diabetes.
MATERIAL AND METHODS: 438 children and adolescents who developed diabetes in the years 1985-2004 were followed for 9.2 ± 3.4 years from the diagnosis. Microalbuminuria was assessed on the basis of timed overnight urine collections performed once per year. Variability of glycated haemoglobin was expressed as a coefficient of variation (%) calculated by dividing standard deviation (adjusted for the number of measurements) by mean of HbA1c.
RESULTS: Microalbuminuria was noted in 99 patients (22.6%) after 8.27 ± 3.3 years of diabetes. In 29 individuals (6.6%), microalbuminuria was persistent. The prevalence of microalbuminuria was not dependent on the period of diabetes diagnosis. During followup, 17 (58.6%) patients with persistent MA reverted to normoalbuminuria. Children without any episodes of microalbuminuria had significantly lower HbA1c variability (8.44%; 95% CI 7.81-9.08%) than those with one (10.28% 95% CI 9.10-11.47%; p = 0.007). The difference of HbA1c variability between patients with and without microalbuminuria persisted after correction by mean HbA1c (p = 0.04). Risk factors for ever developing microalbuminuria during the observation period in multivariate analysis included: mean HbA1c (HR [95% CI]: 1.17 [1.00-1.37; p = 0.05]) and its variability (1.04 [1.00-1.07]; p = 0.05), insulin dose (HR per 0.1 unit*kg- 1*day-1: 0.87 [0.79-0.96]; p = 0.005), presence of arterial hypertension (1.63 [1.07-2.49]; p = 0.02), and age at onset of diabetes (1.15 [1.08-1.21]; p < 0.0001).
CONCLUSIONS: Children who develop microalbuminuria are characterised by poorer and more variable metabolic control, hinting at the importance of interventions aimed at both improvement and stabilisation of HbA1c levels.