NICE published an updated guideline on the management of diabetes in pregnancy in February 2015. For those with gestational diabetes, this recommends that metformin be offered to women in whom blood glucose targets are not met by changes in diet and exercise within 1-2 weeks. Insulin can be offered instead if metformin is contraindicated or unacceptable to the woman, and should be used in addition to metformin if blood glucose targets are not met. Immediate treatment with insulin ± metformin should be offered to those with a fasting plasma glucose level of 7.0mmol/litre or above (or considered at 6.0-6.9 mmol/L if there are complications such as macrosomia or hydramnios) at diagnosis.
The guideline recommends glibenclamide be considered in women with gestational diabetes in whom blood glucose targets are not achieved with metformin but who decline insulin therapy or who cannot tolerate metformin.
The current study looked at outcomes in women with gestational diabetes by using data from a US employer based insurance claims database from 2000 to 2011. Of 110 879 women with gestational diabetes, 8.3% were treated with glyburide (n=4982) or insulin (n=4193). The proportion of these women treated with glyburide increased from 8.5% in 2000 to 64.4% in 2011. After adjusting for maternal comorbidities and risk factors for neonatal outcomes, infants born to mothers treated with glyburide had a higher risk of admission to a neonatal ICU, respiratory distress, hypoglycaemia, birth injury, and being large for gestational age (RR = 1.43; 95% CI, 1.16-1.76) compared with those treated with insulin. The authors say that the results suggest that women with GDM being treated with glyburide may not be achieving adequate glucose control, and they call for further investigation of these observed differences.
The author of an accompanying editorial notes that the study is observational and therefore may be affected by important confounding factors that were not adjusted for. They say however that “This latest study heightens residual concerns about the use of glyburide to treat gestational diabetes mellitus that need to be resolved before this drug should be recommended for continued use in pregnancy.”