Even children whose fathers had type 1 diabetes fared worse, raising doubts about a physiological link.
Children with either a mum or dad with type 1 diabetes do worse at school, suggesting the burden is from a parent with a chronic illness, rather harms from in utero exposure.
Researchers already knew that children did worse at school or on cognitive tests if their mothers had type 1 diabetes, but it was unclear whether that was due to damage to the foetus during pregnancy.
The researchers analysed nationally standardised Danish school test scores from about 622,000 children in grades two, four, six and eight to compare cognitive function over time between children who had at least one parent with diabetes and children who didn’t have a parent with diabetes.
Roughly 2100 children had mothers with diabetes and about 3400 had fathers with diabetes. The rest of the study population had neither parent with diabetes.
Children who had a parent with diabetes had lower mean test scores than the general population, and there was no significant difference in test scores between children whose mother had diabetes or whose father had diabetes.
The researchers said the lower test scores in the parent with diabetes group reflected the negative association of having a parent with a chronic illness rather than a specific adverse effect of maternal T1D during pregnancy on the fetus.
The influence of maternal diabetes has already been widely explored, with high maternal blood sugar levels known to be associated with cognitive dysfunction of the offspring.
“These results are reassuring for women with type 1 diabetes, as one of their main concerns is whether dysregulation of diabetes during their pregnancy may cause impaired cognitive development in their coming children,” the researchers wrote .
“The study presents evidence of an alternative explanation for the previously observed adverse effect of maternal type 1 diabetes during pregnancy on offspring cognitive development,” the researchers wrote in PLOS Medicine.
Ethnicity and race data was not included in the analysis.
The study authors emphasised the importance of glycemic control during pregnancy in preventing various adverse outcomes.
Comparisons of background characteristics showed that children whose mothers had the condition had fewer siblings, their mothers were older and less likely to have a master’s degree or higher educational level, and their parents were less likely to be immigrants or descendants than those whose fathers had the condition. Obstetric and perinatal complications were more often present in pregnancies where the mother had type 1 diabetes.