Definition of gestational diabetes (GDM)
- The diagnosis of gestational diabetes is based on an oral glucose tolerance test (OGTT) in which a 75g load of glucose is given to the patient.
- GDM is diagnosed if (ADA guidelines 2011)
- Fasting ≥92 mg/dl (5.1 mmol/l)
- 1 h ≥180 mg/dl (10.0 mmol/l)
- 2 h ≥153 mg/dl (8.5 mmol/l)
When and how to screen for Gestational Diabetes
There has been no consensus on this issue. The ADA and RCOG (Jan 2011) recommends the following:
Screen for undiagnosed type 2 diabetes at the first prenatal visit in those with risk factors, using standard diagnostic criteria.
In pregnant women not known to have diabetes, screen for GDM at 24–28 weeks of gestation, using a 75-g 2-h OGTT
Screen women with GDM for persistent diabetes 6 weeks postpartum.
Women with a history of GDM should have lifelong screening for the development of diabetes or prediabetes at least every 3 years.
In all other patients urine should be tested for glucose. If glucosuria 1+ or more, plasma glucose levels will be done. OGTT is done if glucose >6.6 more tahn 2 hrs after meal or >7.0 within 2 hrs after meal.
Risk Factors for Gestational Diabetes
- Family history of diabetes
- Medical history of gestational diabetes
- History of large baby more than 4kg
- Previous unexplained stillbirth
- Related to glucose levels
- Congenital abnormalities
- Pre-term labour
- Decrease fetal lung maturity
- Large baby
- Fetal distress and sudden fetal death more common.
- Neonatal Hypoglycemia
- Ketoacidosis (rare)
- Hypoglycemia (too strict control)
- Infection: Wound or endometrial
- Hypertension and pre-eclampsia more common,
- Diabetic retinopathy
- Close surveillance
- Dietary Control: Maintain fasting glucose at <5.5 mmol/L and 2hr post prandial glucose at <6.7 mml/L
- Metformin and Glibenclamide has been used is oral agents
- Insulin still the safest choice.
- Mothers should monitor fetal movement in last 12 weeks of pregnancy
- Ultrasound for congenital abnormalities at 18-22 weeks
- Fetal growth ultrasound 29-33 weeks
- Non stress cardiotocography with umbilical doppler flow may be considered.
- Screen for hypertension.
- Infants fed early and baby screen for hypoglycemia
- Contraception: OCP in complicated diabetes or infection with IUCD.