Acute Hyperglycaemia Impairs Cognitive Function in Children with Iddm

Objective: The effects of acute hyperglycaemia on cognitive function in children remain controversial, This study was designed to investigate the suggestion that acute hyperglycaemia impairs cognition iu IDDM children.Design: To examine this question we studied 12 randomly selected children with IDDM (6 boys, 6 girls, mean age 12.4 years), Cognitive performance was assessed on two occasions at least six months apart (7.4 +/- 1.4 mths, range: 6.3-11.1 mths) under randomised conditions of hyperglycaemia (20-30 mmol/l) on one occasion and euglycaemia (5-10 mmol/l) on the other, Target glucose levels were achieved using a modified clamp technique with subjects and psychologist blinded to the glycaemic level. Cognitive tests chosen to assess performance skills were subtests from the Wechsler Intelligence Scale for Children-3(rd) Edition (WISC-111).Results: No significant learning effect was present, However, there was a reduction in performance IQ at hyperglycaemia compared with euglycaemia (106 +/- 4.3 vs 112 +/- 4.5 IQ points respectively, p<0.05), Under hyperglycaemic conditions the mean decrease in percentile score for performance IQ was 9.5%, Of the 12 children tested, 8 had a decrease in IQ when hyperglycaemic, which was independent of duration of diabetes and long term metabolic control assessed by HbA(1c).Conclusion: Acute hyperglycaemia results in impairment of complex cognitive function in children with IDDM, This may have important implications for school performance.