Gestational diabetes mellitus

Carbohydrate intolerance of varying degrees of severity, with onset or first recognition during pregnancy.


More than 21 million birds are affected by maternal diabetes worldwide each year.

Diabetes develops in roughly 6% to 7% of pregnancies, with approximately 90% attributable to gestational diabetes.

Pre-existing diabetes complicates 0.9% of pregnancies in the US and increases the risk of adverse maternal and neonatal outcomes.

Prevalence of GDM is higher among women of African American, Hispanic, Native American, Asian, and Pacific Islander descent.

Specific risks of uncontrolled diabetes in pregnancy include preeclampsia, congenital defects, preterm delivery, macrosomia, and stillbirth. 

Type one diabetes and pregnancies associated with a 2-5 fold increase risk of major complications including in general anomaly, stillbirth, and neonatal death.

In type one diabetes 50% of infants experience complication such as prematurity, large for gestational age, admission to a neonatal intensive care unit.

Patients with GDM have a 7-fold increased risk for developing type 2 diabetes later in life and require lifelong screening for diabetes.

About 50% of women with GDM go on to develop type 2 DM, on average between 22 and 28 years after pregnancy.

Up to 60% of Latin-American women may develop type 2 diabetes 5 years after being diagnosed with GDM.

Standard treatment is diet and in some cases insulin during pregnancy.

Women with gestational diabetes have a considerable risk of having diabetes later in life.

As many as 70% of women with gestational diabetes will develop type II diabetes by 10 years after delivery (Kim C).

Among parous women with type 2 DM, approximately one-third had a history of gestational DM.

An indicator of the presence of type II diabetes and not type I diabetes.

Associated with increased maternal and perinatal morbidity and increased perinatal mortality.

Complications include neonatal hypoglycemia and maternal hypertension.

Fetal exposure to diabetes during pregnancy can lead to long-term developmental changes that manifest in higher rates of diabetes and obesity in adulthood, adverse cardiometabolic profiles, a greater risk of hospitalizations, medication use, and mortality.

Diabetes in pregnancy may have an influence on neurodevelopmental outcomes with offspring of mothers with diabetes having a lower long-term cognitive function, worse school performance, heightened risk of autism, increased attention deficit/hyperactivity disorder compared with offspring of mothers without pre-existing diabetes.

Diabetic control improves perinatal outcomes.

15% to 47% of such pregnancies are complicated by macrosomia ( 3 to 6 fold increase).

Greater increase in the frequency of shoulder dystocia and other maternal-fetal complications with increasing glucose levels during an oral glucose tolerance test.

Complicates between 3% and 5% of all pregnancies and is associated with an increase in perinatal morbidity.

Associations of milder forms of gestational diabetes with adverse outcomes is unclear.

The Hyperglycemia and Adverse Pregnancy outcome (HAPO) study described a strong continuous association between maternal glucose concentration, increased cord blood, increasing birth weight, increase serum C-peptide and other markers of perinatal complication.

In the HAPO study children of mothers with geststational diabetes versus those without it showed no difference in childhood overweight for obesity defined by BMI index at a median folloup of 11.4 years (Lowe WL).

When diagnosed by 26 weeks associated with an increased risk of autism spectrum disorders.

The Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS) a randomized trial for the treatment of gestational diabetes suggested that treatment reduced serious perinatal complications.

ACHOIS trial indicated that treatment does not reduce rates of symptomatic neonatal hypoglycemia, or jaundice requiring photo therapy.

ACHOIS trial indicated treatment reduced rate of shoulder dystocia when women with mild gestational diabetes were treated compared to untreated patients, 1% vs. 3%.

Increased birth weight and neonatal fat results in increased risk of impaired glucose tolerance and childhood obesity.

In the randomized trial of 958 women with mild gestational diabetes treatment did not significantly reduce the frequency of composite outcome that includes stillbirth, or perinatal death, but it did reduce the risk of fetal overgrowth, shoulder dystocia, Cesarean delivery and hypertension (Landon M).

Controlled trials show the treatment of gestational diabetes improves maternal and perinatal outcomes.

Fetal overgrowth is a complication of gestational diabetes and is associated with an increased risk of birth trauma in the form of brachial plexus injury or clavicular fracture, and of cesarean section to avoid such trauma.

Suggested thresholds of 140 mg % at 1 hour or 120 mg % at 2 hours to reduce the risk of macrosomia.

Management includes nutritional education, exercise, and blood glucose surveillance 4 times daily taken as fasting, or 1 or 2 hours postprandially.

Insulin therapy utilizes starting threshold fasting > 95 mg/dL; 1-hr levels ?140 mg/dL; 2-hr levels ?120 mg/dL.

Initial insulin starting dose: 0.7-1.0 units/kg daily in divided doses

Glyburide’s usual starting dose 2.5-20 mg daily in divided doses, and it likely crosses the placenta.

Metformin can be used in pregnancy.

High-risk women with a diagnosis of diabetes at their first prenatal visit should be considered to have overt type 2 diabetes, rather than GDM.

Post-Partum screening for women with GDM should be performed 6 to 12 weeks after delivery.

Early screening should be performed in high risk women with a previous history of GDM, history of impaired glucose metabolism, or BMI ?30.

Retesting of the above women at 24-28 weeks if initial study is negative for GDM.

Screening tests include oral glucose tolerance tests.

Universal gestational diabetes screening is recommended at 24-28 weeks of gestation.

Criteria for diabetes: Fasting 92 mg/dL; 1-hr value 180 mg/dL; 2-hr value 153 mg/dL.

Initial management includes nutritional counseling, exercise, and blood glucose surveillance.

High-risk women with a diagnosis of diabetes at their first prenatal visit should be considered to have overt type 2 diabetes rather than gestational diabetes.

Lifelong screening and prevention of type 2 diabetes is advocated after gestational diabetes has been diagnosed.

Diagnostic threshold is fasting glycemic level of 126 mg/dL.

Infants borne of mothers with type II diabetes have a 6 fold increase of death within the first year and 11 times the risk of congenital malformations.

Physical activity may lower risk of progression of gestational diabetes to type 2 DM (Bao W et al).


CARDIA study of more than 2700 women suggests presence of gestational diabetes increased the risk of coronary artery calcification later in life, regardless of glucose control following their pregnancy.


Women with previous gestational diabetes had a twofold higher risk of coronary artery calcium if they maintained normal blood sugar levels, later developed prediabetes, or later were diagnosed with Type 2 diabetes many years after pregnancy compared to women without previous gestational diabetes who had normal blood sugar levels.


Diabetes and other health problems that develop during pregnancy serve as early harbingers of future chronic disease risk, particularly heart disease. 


USPSTF recommends screening for gestational diabetes in asymptomatic pregnant persons at 24 weeks of gestation or after.



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