Treatment of Pregnancy Related Diabetes

What is the problem and what is known about it so far?
Women with gestational diabetes have high blood sugar levels during pregnancy which resolves after delivery. Women with gestational diabetes have more difficult deliveries and their babies have more difficulty with regulation of blood sugar and jaundice in the newborn period. Whether treatment of gestational diabetes reduces the risk of complications is not known.

Why did the researchers do this particular study?
These researchers wanted to know whether treatment of gestational diabetes decreased complications for both mothers and infants during delivery and after birth.

Who was studied?
1000 pregnant women in the second or third trimester who had been diagnosed with diabetes during pregnancy.

How was the study done?
Pregnant women were diagnosed with gestational diabetes using a glucose tolerance test (drinking a sweet liquid with a known amount of glucose then checking their blood sugar). Women were then randomly assigned to one of 2 groups: the treatment group knew their blood sugar test results and were treated with dietary counseling and advised to follow a diabetic diet, monitor their blood sugars, and receiv closer fetal monitoring. If needed, they received insulin to get their blood sugar into the normal range. In the standard care group, the women were not aware they had gestational diabetes and were only treated if symptoms arose. The risk of having a newborn with a complication was compared between the treatment group and the standard care group.

What did the researchers find?
Treatment of gestational diabetes reduced the overall rate of serious complications (stillbirth, neonatal death, or birth injury) in the newborn infants by over 60% (1% in the treated women versus 4% in the standard care group). Infants of the mothers treated for gestation diabetes were smaller (by 1/3 pound) and less likely to weigh over 8.8 pounds. Infants of treated mothers were more likely to go to the special care nursery (71% versus 61%), although there was no increased risk of other complications. Women in the treated group were more likely to have labor induced (39% in the treatment group versus 29% in the standard care group) but less likely to have a diagnosis of preeclampsia (12% versus 18%). Women that were treated for gestational diabetes had less weight gain during pregnancy (approximately 3 ½ pounds less). Women that were treated for gestational diabetes had less depression and improved measures of overall health when questioned.

What were the limitations of the study?
Both the patients and the providers knew who had gestational diabetes, which may have led to other changes in care that provided the beneficial outcomes rather than treatment itself. Women who were in the routine care group were not informed that their blood sugars were elevated. It is not clear what aspects of care allowed for the improved outcome.

What are the implications of the study?
Treating women with gestational diabetes using dietary counseling, close monitoring of blood sugars, and insulin therapy as needed reduces infant complications and improves maternal health during pregnancy and in the period after birth. The results of this study strongly point to the positive effects of screening for and treatment of gestational diabetes.

Summarized by Anna Benvenuto, College of Medicine, University of Vermont
Summarized from "Effect of Treatment of Gestational Diabetes Mellitus on Pregnancy Outcomes". Crowther, C. et al. New England Journal of Medicine, June 16, 2005, Volume 352, pages 2477-2486.