Gestational diabetes mellitus

Rinat Gabbay Ben-Ziv, Moshe Hod*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review


GDM is defined as "carbohydrate intolerance of variable severity with onset or first recognition during pregnancy." The prevalence of GDM is about 2-5% of pregnancies and it depends of the prevalence of to type 2 DM in the population. The pathogenesis of GDM is a combination of insulin resistance (of normal pregnancy and a chronic form in GDM patients), B cell dysfunction of autoimmune origin and/or from genetic mutations. GDM is associated with chronic insulin resistance, genetic changes and placental transport differences compared to non-diabetic pregnant women. The pathogenesis ofGDMresembles that of type 2 DM. Indeed, a large percentage ofGDM patients turn in to type 2 DM in the years after pregnancy. GDM has both maternal and fetal complications: for the mother the risk is mainly long term - the progress to type 2 DM and metabolic syndrome. For the fetus there are both short and long term complications - fetal death, aberrant fetal growth mainly macrosomia with its effect on delivery and risk of shoulder dystocia and metabolic/haematologic changes (hypoglycaemia, hypokalaemia, hyperbilirubinaemia, hypocalcaemia, polycythaemia and respiratory distress syndrome). The long term risks for the fetus are adverse neurological and cognitive outcomes and mainly early onset metabolic syndrome. For most women, glucose screening should be conducted at 24-28 weeks- gestation with the use of a 50-g oral glucose load. A value of 7.8 mmol/L (140 mg/dL) or greater necessitates a full diagnostic 100-g oral glucose tolerance test (GTT). Testing at this time not only enables the obstetrician to assess glucose tolerance in the presence of the insulin-resistant state of pregnancy but, should GDM be diagnosed, permits treatment to begin before excessive fetal growth has occurred. Those women who seem to be at high risk for GDM should be tested by OGTT as early as possible. If the initial screen is negative, they should be retested at 24-28 weeks- gestation. Once a diagnosis of GDM is made, women should be under close perinatal surveillance. Diet treatment is advised in all. The goal of treatment is reducing the fetal and maternal morbidity and mortality related with GDM. The exact glucose values needed to do so are still not clear. The decision to start pharmacological treatment depends on the glycaemic controlwith diet treatment and gestational age at diagnosis. The options for pharmacological treatment are insulin, which is considered the most acceptable treatment, or oral anti-diabetic drugs such as metformin and glyburide. It is extremely important to maintain good glycaemic control in order to reduce maternal and fetal morbidity and mortality during pregnancy and delivery. Concerning the time and mode of delivery, there is a higher rate of cesarean section in GDM women. The decision whether and when to induce delivery depends on gestational age, estimated fetal weight and maternal glycaemic control and Bishop score. Themain reasons for timed delivery are fear of fetal death and shoulder dystocia. When estimated fetal weight is 4,500 g or more, caesarean delivery may be considered because it may reduce the likelihood of permanent brachial plexus injury in the infant. Future research is needed regarding prevention of GDM, treatment goals and effectiveness of interventions, guidelines for pregnancy care and prevention of long term metabolic sequelae for both the infant and the mother.

Original languageEnglish
Pages (from-to)245-269
Number of pages25
JournalFetal and Maternal Medicine Review
Issue number3
StatePublished - Aug 2008


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