The lack of convincing evidence for benefit from treating ‘mild GDM’ has also been a source of controversy concerning the value of efforts to identify women with GDM. However, the results of a randomized clinical trial (RCT) conducted in Australia and reported recently help to clarify this issue   1 . Some of the key findings from this report are summarized in the Table:

Treatment of GDM reduces adverse outcomes

The RCT demonstrated that treating GDM (diagnosed when the fasting plasma glucose was 4.8 + 0.7 mmol/L and the two-hour value after a 75 gm oral glucose load was from 7.8-11.0 mmol/L) significantly reduced the likelihood of serious neonatal morbidity (complications) compared to outcomes in those receiving routine prenatal care. Birth weight and the frequency of delivering babies that were large for gestational age (LGA) or macrosomic (> 4.0 kg birth weight) were also less in the treatment/intervention group. Treatment included individualized medical nutrition therapy, daily self-monitoring of blood glucose and insulin when needed (20% of cases). Other RCT studies of similar design are in progress.

New approaches to treatment
There is uncertainty about “the level of hyperglycaemia, short of overt diabetes that conveys increased perinatal risk”   2 . However, there is general consensus that in women with a diagnosis of GDM that have clearly elevated fasting and/or one or two hours after meal blood glucose concentrations at diagnosis, lowering the maternal blood glucose levels to near normal concentrations may reduce the risk of excessive fetal growth to approximate the risk in the general population   3   4 and a major objective of treating GDM is to reduce adverse perinatal events, primarily those associated with excess weight or adiposity of the newborn (Caesarean delivery, birth trauma, neonatal morbidities).

Medical nutrition therapy remains the initial and primary modality for treatment of GDM. When optimal glycaemia is not achieved or maintained, additional treatment with biosynthetic human insulin has been used globally for many years. Following the demonstration that the sulfonylurea, glyburide (glibenclamide), crosses the placenta to a very limited extent   5 , a randomized clinical trial was carried out comparing glycaemic control and outcomes in women with GDM treated with human insulin or glyburide (glibenclamide)   6 . Comparable results were found in the two groups. Additional reports with smaller numbers of subjects have been published subsequently that in general confirm the results of the original study.

The participants of the Fifth International Workshop Conference on GDM cautioned that the findings with glyburide (glibenclamide) could not be extrapolated to other sulfonylurea agents or other classes of oral medication. They further emphasized the need for continued close surveillance of maternal glycaemia during all forms of treatment of GDM to assure that treatment goals are met and sustained   4 .