Aims/hypothesis: Good metabolic control in diabetic children is already crucial before puberty to prevent diabetic complications later in life. However, tight metabolic control could increase the risk of severe hypoglycaemia, which might be responsible for impaired intellectual performance later in life. The purpose of this prospective longitudinal study was to evaluate the relevance of long-term metabolic control and hypoglycaemia possibly affecting the intellectual development of young children with Type I (insulin-dependent) diabetes mellitus.
Methods: The intellectual development in 64 diabetic children between the ages of 7 and 16 years was assessed at least four times using the German version of the Hamburg Wechsler intelligence scale for preschool children, Children-Revised and by the "Adaptives Intelligenz Diagnostikum" (Adaptive Intelligence Diagnosticum). Data were analysed longitudinally compared with a control group.
Results: A significant decline in performance by age 7 and in verbal intelligence quotient between age 7 and 16 years was observed in diabetic boys diagnosed before the age of 6 but not in those diagnosed later and not in diabetic girls. The deterioration of intellectual performance in boys diagnosed at a very young age was not associated with the occurrence of severe hypoglycaemic episodes but was correlated with the degree of metabolic deterioration at diagnosis and with high long-term average of glycated haemoglobin.
Conclusion/interpretation: Our study in diabetic children shows that the male sex, diagnosis at a young age, metabolic condition at diagnosis and long-term metabolic control, rather than experienced hypoglycaemic attacks are risk factors for intellectual development.