Maternal blood glucose in diabetic pregnancies and cognitive performance in offspring in young adulthood: a Danish cohort study.

AIMS: Maternal diabetes is a known risk factor for perinatal complications, but there are little data on consequences for long-term intellectual outcome in offspring. We assess cognitive performance in military conscripts according to maternal blood glucose levels during pregnancy.
METHODS: We identified a cohort of 60 Danish male offspring of insulin-treated diabetic mothers born between 1976 and 1984 and followed this cohort to military conscription. From medical records, we extracted data on all available values of maternal blood glucose categorized as fasting and non-fasting and by day in pregnancy, together with maternal White class, smoking habits and socio-economic status. The main outcome was cognitive performance at conscription measured with a validated intelligence test. The association between maternal blood glucose level and cognitive performance was assessed by multivariate linear regression and a fitted fractional polynomial.
RESULTS: Median fasting blood glucose values in the second half of pregnancy was negatively associated with cognitive scores at conscription [adjusted coefficient -1.7; 95% confidence interval (CI) -3.0; -0.4]. Restriction to only first-born sibling slightly strengthened the association (coefficient -1.9; 95% CI -3.3; -0.5), but after exclusion of two pregnancies with the blood glucose > 10 mmol/l the association became insignificant (coefficient -0.6; 95% CI -2.6; 1.4).
CONCLUSIONS: Maternal blood glucose level during diabetic pregnancy is negatively associated with cognitive performance in offspring at military conscription. In pregnancies with fasting blood glucose levels below 10 mmol/l, the association is weak and considered to be without clinical relevance.