Gestational Diabetes

Gestational diabetes is a state of insulin resistance induced by the metabolic strain of pregnancy

Aetiology

Risk factors

• Previous gestational diabetes

• Previous macrosomic baby (≥ 4.5kg)

• BMI > 30

• Ethnic origin (black Caribbean, Middle Eastern and South Asian)

• Family history of diabetes (first-degree relative)

Investigations

Oral glucose tolerance test (OGTT)

• The screening test of choice for gestational diabetes is an oral glucose tolerance test (OGTT)

• An OGTT is used in patients with risk factors for gestational diabetes, and also when there are features that suggest gestational diabetes:
• Large for dates fetus
• Polyhydramnios 
• Glucose on urine dipstick

• Usually diagnosed at 24-28 weeks of gestation

Management

• Treatment is with a low GI diet, plus metformin and insulin if required

• The risk of future type 2 diabetes can be addressed with diet, lifestyle and metformin therapy

• Women with gestational diabetes should give birth no later than 40+6 weeks of gestation

• GDM usually tends to disappear as soon as the placenta is delivered

Complications

• There is a clear association with raised blood glucose levels in pregnancy and complications such as congenital malformations, large baby size and obstetric complications with increased rates of miscarriage and stillbirth

• Hyperglycaemia in pregnancy is associated with an increased later risk of developing type 2 diabetes in up to 50% of women over the next 5-10 years