The CGMS in GDM Labor and Delivery Study

Glucose control during labor is important for both fetus and mother. During labor and delivery, the goal is to maintain the sugars in the normal range as safely as possible as increased blood sugars 4-6 h prior to delivery leads to increased rates of hypoglycemia in the neonate. Neonatal hypoglycemia is a risk for the offspring of pregnant women with diabetes and occurs when fetal pancreatic hyperplasia is acutely stimulated by a high fetal glucose level derived from maternal hyperglycemia during labor. The maternal blood glucose level during delivery is a predictor of the neonatal blood glucose level. Modern continuous glucose monitoring (CGM) systems can capture the direction and magnitude of short-lived changes in interstitial glucose levels and are therefore useful for assessing glucose variability more accurately than self-monitoring blood glucose (SMBG) measurements. Indeed, it has already been demonstrated that intermittent blood glucose monitoring underestimates the number of hyperglycemic events, because blood glucose excursions can peak at different times of day. CGMs can help identify glycemic patterns in pregnancy, obtain and maintain glucose targets, and reduce hypoglycemia. Strict glycemic control during labor and delivery may reduce the risk of neonatal hypoglycemia. Two groups have reported on the use of CGM in type 1 diabetics during labor in small pilot studies. Another study looked at effects of maternal glucose levels in insulin-treated women during labor and delivery (2 to 8 h before birth) and resultant neonatal hypoglycemia. The researchers found that maternal hyperglycemia before delivery was correlated with neonatal hypoglycemia. Although more studies are needed, CGM use has promise as a therapy to improve outcomes in pregnancies associated with diabetes. In this study, the investigators plan to explore whether the use of blinded glucose monitoring during labor, delivery, and early postpartum supplementary to normally monitored plasma glucose measurements in women with gestational diabetes (GDM) would provide useful information to improve glycemia during labor in this diabetic population. All CGM data will be masked and therefore not available to participants, clinicians, or researchers at the time of delivery. Participants otherwise will receive standard clinical care. The blinded glucose monitoring data on glycemia throughout labor and post-delivery will be retrospectively assessed.