Gestational Diabetes Mellitus

Dalia Baliutavičienė, Milda Jaržemskienė


Gestational diabetes mellitus (GDM) is carbohydrate intolerance resulting in hyperglycaemia of variable severity with onset or first recognition during pregnancy

Prevalence. Gestational diabetes is the most common metabolic complication of pregnancy. The prevalence in Europe is 0.15-4%, in Lithuania   - approximately 1.5%.

Etiology. Women with GDM are a heterogenous group. For most of them the glucose intolerance occurs in the second trimester of pregnancy due to increasing levels of pregnancy hormones with growing insulin resistance and impaired ability to increase insulin secretion. Some pregnant women are in the early stage of diabetes.

Risk factors for GDM and indication for glucose tolerance test in pregnancy. 
  • glycosuria
  • polyhydramnios
  • age ≥35 years
  • GDM in previous pregnancy
  • overweight
  • previous macrosomia (≥4 kg)
  • family history of diabetes
  • previous fetal malformations



GDM is diagnosed by an oral 75-g glucose tolerance testing (OGTT) according to the WHO recommendations when the 2-hour value is ≥ 7.8 mmol/l. The OGTT should be performed between the 24 and 28 week of gestation in the morning after at least three days of unrestricted diet (greater than 150 g of carbohydrate daily), usual physical activity, but preceded by an overnight fast of 8-14 hours.

Perinatal complications and sequelae

Maternal complications

Management during pregnancy


·      With good control, the women may be delivered vaginally at term. Delivery at 38 weeks is recommended if fetal macrosomia is diagnosed.

·      For those who require insulin, blood glucose levels should be monitored at 4-h intervals during labour. Women with GDM rarely need insulin during labour or postpartum.

Management after pregnancy

Glucose tolerance should be re-evaluated in the mother at 6-12 weeks postpartum to establish a final diagnosis (table 1).

Finally diagnosis after GDM using 2-hour OGTT

2-h value



<7.8 mmol/l

7.8-11.0 mmol/l

≥11.1 mmol/l


normal glucose tolerance (“previous GDM”)

impaired glucose tolerance


If the postpartum evaluation does not indicate diabetes, GTT should be assessed annually. Lifestyle behaviours aimed at reducing weight and increasing physical activity should be recommended.


1.      Metzger BE, Coustan DR. Summary and recommendations of the Fourth International Workshop-Conference on Gestational Diabetes Mellitus. Diabetes Care 1998;21(suppl 2):B161-7.

2.      American College of Obstetricians and Gynecologists. Diabetes and pregnancy: ACOG Technical Bulletin No 200. Washington, DC: ACOG; 2000.

3.      American Diabetes Association. Gestational diabetes mellitus. Diabetes Care 2004;27(suppl 1):S88-90.