Gestational diabetes is a form of diabetes that may develop during pregnancy. In addition to a genetic predisposition, relevant factors are especially being overweight/obese, lack of exercise and unfavorable dietary habits. The risk of gestational diabetes and its negative consequences for the unborn child can frequently be influenced by suitable measures such as a timely change in diet and increased exercise. A current study published in the Journal of Clinical Endocrinology & Metabolism underscores the great importance of timely prevention and intervention . It was supported by the German Center for Diabetes Research, the German Research Foundation and the Helmholtz Alliance.
Slowed fetal brain response after maternal food ingestion in the case of gestational diabetes
Forty pregnant women from the diabetes clinic and women's clinic at Tübingen University Hospital participated in the study, including 12 who had gestational diabetes. The study comprised examinations at three measurement time points: The initial measurement was for fasting glucose levels. Then the women ingested 75 grams of a sugar solution. The second examination took place 60 minutes after the glucose uptake; the third measurement took place two hours after the glucose uptake. At each measurement time point a fetal magnetoencephalography measured the fetal brain response to a repeated auditory stimulus, and the response time of the fetal brain was determined. In addition, at each measurement time point the mother was tested for sugar and insulin in the blood.
The result: One hour after the glucose uptake, the researchers found a significantly slower fetal brain response to the auditory stimuli in the group of children of women with gestational diabetes compared to the children of the control group of women without gestational diabetes (296 ± 82 ms vs. 206 ± 74 ms, P = 0.001). At the other two measurement time points, however, there was no significant difference between the two groups. The temporarily slowed brain response in the unborn children of the participants with gestational diabetes was significantly associated with elevated glucose and insulin levels of the expectant mothers.
Maternal insulin resistance may affect the brain metabolism of the unborn child
The authors conclude that the mother’s metabolism directly affects the brain function of the fetus and that a gestational diabetes may induce insulin resistance in the brain already of the unborn child. They explain this as follows: In children of healthy mothers, after maternal uptake of the sugar solution there is a rise in glucose and insulin in the brain, which leads to an activation and improvement of the fetal neural brain activity. This effect does not occur in the unborn children of mothers with gestational diabetes. The researchers suspect that these children develop an insulin resistance already in utero when the mother has a temporary hyperglycemia.
Possible imprinting for later obesity and type 2 diabetes in utero
If the researchers’ hypothesis is correct, this could be tantamount to imprinting the fetal metabolism already in utero, and the suspected insulin resistance in the fetal brain could increase the child’s risk for diabetes and obesity later in life. The current state of research on the importance of insulin in the human brain and the effects of insulin resistance there was summarized by the research group in an overview article in the prestigious journal Nature Reviews Endocrinology .
 Linder K et al. Gestational Diabetes Impairs Human Fetal Postprandial Brain Activity. The Journal of Clinical Endocrinology & Metabolism 2015: jc20152692. DOI:10.1210/jc.2015-2692
 Heni M et al. Impaired insulin action in the human brain: causes and metabolic consequences. Nature Reviews Endocrinology 2015. DOI:10.1038/nrendo.2015.173