gestational%20diabetes%20mellitus
GESTATIONAL DIABETES MELLITUS
Gestational diabetes mellitus (GDM) is any degree of glucose intolerance with onset or first recognition during pregnancy.
Hyperglycemia in pregnancy may be suggested by the presence of glycosuria, a fetus that is large for date, or polyhydramnios.
Overt diabetes mellitus may be found in women presenting with risk factors for type 2 diabetes during the first prenatal visit (before 13 weeks of gestation).

Pharmacotherapy

Insulin Preparations

  • Insulin is the 1st-line pharmacotherapy recommended for gestational diabetes mellitus (GDM) when medical nutrition therapy (MNT) fails to maintain glycemic control
    • Given also to women with GDM when Metformin is contraindicated or unacceptable to patient
  • Human insulin should be used in pregnant women because it is the least immunogenic
    • Rapid-acting insulin analogs develop antibodies similar to human insulin
    • Insulin with low antigenicity minimizes transplacental transport of insulin antibodies
  • Multidose regimen of insulin administration may be needed for better control of blood glucose levels
  • Individualize therapy and regularly adapt to the changing needs of pregnancy to meet glycemic control goals
  • Exact time course of each insulin will depend on each particular preparation, presence of antibodies in the patient and site of inj
  • Immediate treatment with Insulin/, with or without Metformin, is considered in women with GDM who have a fasting plasma glucose of 6-6.9 mmol/L with complications eg macrosomia or hydramnios and is offered to women with GDM who have a fasting plasma glucose of  ≥7 mmol/L at diagnosis
Metformin
  • May be given in women with history of GDM and prediabetes
  • May also be given if diet and exercise within 1-2 weeks failed to meet blood glucose targets and for patients not in their 1st trimester who cannot use or refuse Insulin or Glibenclamide 
  • Metformin crosses the placenta but risk of neonatal hypoglycemia and maternal weight gain may be lower than with Insulin
  • Initial dose is 500 mg orally once daily with food, titrated up to a max dose of 2.5 g/day
  • Long-term safety data are not available 

Glibenclamide (Glyburide)

  • May be used as alternative for GDM patients who are unable or unwilling to take Insulin, who cannot tolerate Metformin, or whose blood glucose targets are not met with Metformin but refuses Insulin
  • Useful adjunct to MNT and physical activity regimens when additional treatment is necessary to maintain appropriate glucose levels
    • Safe and effective in controlling glucose levels in >80% of patients with GDM
  • Has shown minimal transplacental transfer and has not been associated with excessive neonatal hypoglycemia
  • Initial dose is 2.5 mg orally once daily before meals, titrated up to a max dose of 20 mg/day  
  • Long-term safety data are not available 

Non-Pharmacological Therapy

Maternal Surveillance

Hyperglycemia Detection

  • Goal: Detect hyperglycemia and maintain good glycemic control throughout pregnancy to decrease maternal and fetal adverse outcomes
    • High maternal glucose increases the risk of: 
      • Higher frequency of primary cesarean section delivery
      • Preeclampsia  
      • Preterm delivery
      • Shoulder dystocia or birth injury  
      • Fetal macrosomia  
      • Neonatal hypoglycemia  
      • Hyperbilirubinemia  
      • Intensive neonatal care
  • Recommend daily self-monitoring of blood glucose (SMBG) over intermittent office monitoring
    • Done fasting, pre-meal and either 1 or 2 hours after each meal, at bedtime if indicated
    • HbA1c should be used as a secondary measure and if can be obtained without developing hypoglycemia, target HbA1c level in pregnancy is 6-6.5% with optimal level of <6% as pregnancy continues
  • Suggested glycemic control for patients with gestational diabetes mellitus (GDM):
  •  

    Goal
    Preprandial glucose, plus either
     ≤5.3 mmol/L (95 mg/dL)
     1-hour postprandial blood glucose  ≤7.8 mmol/L (140 mg/dL)
     2-hour postprandial blood glucose  ≤6.7mmol/L (120 mg/dL)

Fetal Surveillance

  • Should be individualized based on severity of hyperglycemia in the mother and presence of risk factors
    • It is not recommended to routinely monitor fetal well-being before 38 weeks unless risk for fetal growth restriction exists; however, a more frequent fetal health assessment is recommended if comorbid factors are present 
  • Mother should be taught to monitor fetal movement in the last 8-12 weeks of pregnancy and to report any reduction in movement
  • If GDM is diagnosed during 1st trimester, it is recommended to do ultrasound at 18-22 weeks to detect congenital anomalies
  • Non-stress testing, contraction stress testing, and/or biophysical profile assessments should be recommended to GDM patient with poor glycemic control and co-morbid conditions
  • Assess fetal response to GDM by ultrasound measurement of fetal abdominal circumference during the 2nd trimester, early 3rd trimester and repeated every 2-4 weeks to guide management decisions
  • Lower goals for glycemic control may be recommended for bigger fetal abdominal circumference
  • Intensify fetal surveillance when pregnancy is beyond 40 weeks of gestation

Medical Nutrition Therapy (MNT)

  • Cornerstone of GDM management
    • Preconception care should be accessible to all females with pre-existing DM to ensure adequate nutrition and glucose control prior to conceiving, during pregnancy, and postpartum
  • Patient should be counseled about individual MNT based on their height and weight
  • MNT is best prescribed by a registered dietitian or a healthcare provider with experience in managing GDM patients
  • MNT should include adequate calories and nutrition to meet needs of mother and fetus
    • Avoid inappropriate weight loss or gain and avoid ketonuria
    • MNT should be adjusted to meet glycemic control goals
  • Obese patients may benefit from calorie restriction (approximately 25 kcal/kg actual body weight/day)
    • Shown to decrease hyperglycemia and triglycerides and does not seem to increase ketonuria
  • Carbohydrate reduction to 35-40% of daily energy intake has been shown to decrease hyperglycemia and improve maternal and fetal outcomes
  • More complex carbohydrates, more fiber, lean protein, oily fish, and a balance of polyunsaturated fats and monounsaturated fats are recommended
  • If MNT fails to meet glycemic control goals within 1-2 weeks, Insulin administration should be considered

Moderate Exercise

  • Physical activity is encouraged unless medical or obstetrical contraindication exists or glycemic control is worsened by activity
  • Regular aerobic exercise for at least 30 min daily has been shown to lower maternal blood glucose levels

Other Considerations

  • Women with history of GDM who had prediabetes should be offered intensive lifestyle intervention or Metformin to prevent diabetes
  • Psychosocial assessment is also recommended to detect onset of anxiety, depression, stress and eating disorders
  • GDM is not an indication for cesarean delivery
  • GDM is also not a consideration for delivery before 37 weeks of gestation unless there is maternal or fetal compromise
    • Patients with type 1 or type 2 diabetes without complications are advised to have an elective birth through labor induction or cesarean section if indicated between 37 and 38 weeks
  • Gestation past 38 weeks increases risk of macrosomia
    • Women with GDM are advised to give birth not later than 40 weeks and are offered elective birth if they have not delivered by this time, though elective labor induction is not necessary in women with good glycemic control and no other obstetric indication
  • All women, including those with GDM, are encouraged to exclusively breastfeed
    • It may decrease offspring obesity and prevent development of type 2 DM
    • Except for Metformin and Glibenclamide, other oral hypoglycemic agents should be avoided while breastfeeding 
  • Early feeding of the baby to reduce the risk of neonatal hypoglycemia
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