Evidence Supports Treatment of Mild Gestational Diabetes

The current treatment of mild gestational diabetes mellitus (GDM) results in fewer cases of preeclampsia, shoulder dystocia, and macrosomia but seems to have no effect on neonatal hypoglycemia or future poor metabolic outcomes, concluded a systematic review and meta-analysis that summarized evidence about the benefits and harms of treating mild GDM.¹
   
The incidence of GDM in the United States ranges from 1.1% to 25.5% of all pregnancies, with variations caused by differences in diagnostic criteria and patient characteristics.¹ Initial management of GDM includes dietary modifications, glucose monitoring, and moderate exercise. If blood glucose levels remain uncontrolled, treatment with oral medication or insulin may be required.
   
Eleven studies were included in this review, 5 of which were randomized controlled trials and 6 of which were cohort studies in women with no history of diabetes mellitus. All of the included studies compared no treatment with diet modification, glucose monitoring, and as-needed insulin.
   
There was moderate evidence that treatment of GDM resulted in fewer recorded cases of preeclampsia, shoulder dystocia, and macrosomia, defined as a birthweight exceeding 4000 g. The review authors acknowledged that these outcomes may be of intermediate importance compared with outcomes such as prematurity or brachial plexus injury and reported that there was insufficient evidence to determine whether any important differences existed between the study groups for the outcomes of greater clinical interest. The authors also suggested that factors such as maternal weight and gestational weight gain may be associated with greater risk of intermediate outcomes than GDM, especially in conjunction with modestly elevated blood glucose levels.
   
As expected, women whose GDM was treated had more prenatal visits than women whose GDM was untreated, indicating a greater use of resources and probable higher costs of care for women in the treatment group. The rates of cesarean delivery, neonatal hypoglycemia, and admission to a neonatal intensive care unit were similar between study groups, but the evidence was low. In addition, there was no difference in the rates of small-for-gestational-age neonates between study groups.
   
The overall evidence supports the treatment of mild GDM, which results in fewer cases of preeclampsia, macrosomia, and shoulder dystocia. However, the authors found that the risk of these outcomes attributed specifically to GDM is low, especially when glucose levels are modestly elevated. Maternal weight and gestational weight gain probably are associated with greater risk for these outcomes than mild GDM alone, concluded the review authors.

Pertinent Points:
- Treatment of gestational diabetes mellitus (GDM) is associated with a lower incidence of preeclampsia, macrosomia, and shoulder dystocia.
- Current evidence does not support a treatment effect of GDM on clinical neonatal hypoglycemia or future poor metabolic outcomes in offspring of women with GDM.
- The harm related to the treatment of mild GDM is limited to an increase in resource use and related costs.
 

References:

1. Hartling L, Dryden DM, Guthrie A, et al. Benefits and harms of treating gestational diabetes mellitus: a systematic review and meta-analysis for the U.S. Preventive Services Task Force and the National Institutes of Health Office of Medical Applications of Research. Ann Intern Med. May 28, 2013. doi: 10.7326/0003-4819-159-2-201307160-00661. [Epub ahead of print]