Fasting glucose in early pregnancy detects diabetes risk

A study of 25,505 women at 24-32 weeks of pregnancy published in May 2008 found a strong link between fasting glucose levels at the high-end of the normal range and complications during pregnancy. Dr Shlomit Riskin-Mashiah and his colleagues in Haifa thought screening at 24-32 weeks would give insufficient time for treatment, so they looked at 6,129 women who had similar levels of fasting glucose in the first 12 weeks of pregnancy. Their study excluded women who had diabetes before pregnancy, gave birth before 24 weeks or had a fasting glucose greater than 5.8 mmol/L. The study was published in the September issue of Diabetes Care.

As in the earlier study, women were ranked into groups according to their fasting glucose levels, ranging from less than 4.1 mmol/L up to 5.8 mmol/L. With increasing levels the frequency of diabetes during pregnancy increased from 1.0% in the lowest group to 11.7% in the highest. The frequency of ‘large for dates’ babies and of caesarean section also increased with fasting glucose levels. There was only a slight increase in risk of developing diabetes once obesity before pregnancy was taken into account, but an increased risk of having a large baby remained even after excluding women who developed diabetes.

It seems that screening for diabetes earlier than the last third of pregnancy, which is currently the custom, might be beneficial. They suggest that a large trial is needed to confirm their findings and to evaluate whether diet and exercise might reduce diabetes in those at highest risk.