The CGMS in GDM Labor and Delivery Study
Condition: Gestational Diabetes Mellitus in Pregnancy
MeSH terms: Diabetes, Gestational; Pregnancy in Diabetics
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      Planning management for a diabetic parturient during labor and delivery is particularly
      challenging because of the demands of labor, dietary restrictions, and potential for
      operative delivery. The main goals can be summarized as: ensuring the avoidance of maternal
      hypoglycemia or hyperglycemia (which can increase the risk of neonatal hypoglycemia),
      ensuring the safe use of measures to manage glycemic control, and the provision of effective
      analgesia for labor. Currently available international guidelines for the peripartum
      management of pregnant women with diabetes focus on rigorous intrapartum glycemic control.
      Maternal hyperglycemia in women with pregestational and gestational diabetes mellitus can
      cause hypoglycemia in the neonate following delivery. In women with diabetes, maternal
      hyperglycemia leads to hyperplasia of pancreatic β cells in the fetus and an increase in
      fetal insulin concentrations. When the continuous supply of glucose is stopped after
      delivery, the neonate is at risk of developing hypoglycemia, which if untreated can have
      serious neurological consequences. The increase in fetal insulin also contributes to the
      excess growth of the fetus in mothers with hyperglycemia. Avoiding intrapartum maternal
      hyperglycemia may prevent fetal hyperglycemia and reduce the likelihood of subsequent
      neonatal hypoglycemia. A further potential concern relates directly to the woman. Immediately
      after delivery, postpartum insulin requirements decrease dramatically as a result of the
      rapid decrease in diabetogenic placental hormone levels and resulting dissipation of
      pregnancy-induced insulin resistance. Pregnant women with diabetes may be at greater risk of
      hypoglycemic episodes because awareness of the symptoms of hypoglycemia is reduced, and this
      is further exacerbated by tight glycemic control .

      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, and a high blood
      glucose level in the mother is associated with neonatal hypoglycemia. Continuous glucose
      monitoring (CGM) use appears to be safe and effective in pregnancies complicated by diabetes.
      Modern 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. CGM helps with treatment adjustments in pregnancies associated with
      diabetes. Strict glycemic control during labor and delivery may reduce the risk of neonatal
      hypoglycemia. In principle, "real-time" CGM might allow more rapid adjustment of insulin
      dosing and, thereby, yield better glycemic control than is possible with intermittent glucose
      monitoring. Two groups have reported on the use of CGM during labor in small pilot studies.
      Stenninger et al. reported that CGM was well tolerated in their 15 subjects and that elevated
      maternal glucose levels in the last 2 hours before delivery correlated with the need for
      intravenous glucose in the newborn. They found that multiple glycemic indices correlated
      positively with the need for neonatal intravenous glucose infusions. Iafusco et al. used
      real-time CGM in 14 subjects to guide insulin therapy during labor and found no cases of
      neonatal hypoglycemia. Another study looked at effects of maternal glucose levels in
      insulin-treated women during labor and delivery (2 to 8 hours before birth) and resultant
      neonatal hypoglycemia. In the this study, 45% (27/60) of women in the CGM group were compared
      with 100% (59/59) in the control group. Among women in the CGM arm, 10 infants developed
      hypoglycemia compared with 27 in the non-CGM group (37% vs. 46%, respectively; P = 0.45). 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.
    

Intervention name(s): Blinded CGM
Intervention type(s): Device
Intervention description(s): CGM that records blood glucose but is not visible to patient or provider in real-time
Other intervention name(s): Dexcom G6 Pro
Intervention model: Single Group Assignment
Intervention model description: Blinded continuous glucose monitor will be compared with routine blood glucose monitoring
Masking: None (Open Label)
Primary purpose: Supportive Care
Keywords: continuous glucose monitoring; labor; post-delivery