Pregestational diabetes is type 1 diabetes or type 2 diabetes that exists before pregnancy. The most common form is type 2 diabetes.
Classification of pregestational (overt) diabetes
| Class | Key Feature |
|---|---|
| B | Diabetes begins after age 20 and has been present < 10 years. No vascular disease |
| C | Diabetes begins at 10–19 years or has been present 10–19 years. No vascular disease |
| D | Diabetes begins before age 10, or duration > 20 years, or background (benign) retinopathy |
| F | Diabetic nephropathy (kidney disease) |
| R | Proliferative retinopathy |
| H | Coronary artery disease |
| T | Previous renal transplant |
- Treatment
- Preconception:
- Normalize blood glucose before conception and during early pregnancy
- Folate 400 ug/day pre-conceptually and during early pregnancy
- Insulin
- Insulin requirement increases for type 1 diabetes as pregnancy progresses
- Most patients with type 2 diabetes are switched from oral glucose lowering agents (OGLAs) to insulin
- First-trimester
- Second-trimester
- Serum AFP at 16-20 weeks
- Anomaly scan at 18-20 weeks to detect neural tube defects and other abnormalities
- Third-trimester
- Weekly visits to monitor glucose and evaluate for preeclampsia
- Serial ultrasound every 3-4 weeks to evaluate macrosomia, intrauterine growth restriction, and amniotic fluid levels
- Delivery
- Assess lung maturity at 37 weeks
- Induce delivery after 37 completed weeks if the fetal lungs are mature
- Induce delivery at 38 – 39 weeks if lung maturity cannot be tested
- Caesarean delivery is preferred for macrosomia, severe hypertension, overt diabetes within B or C white classification, or vascular disease
- Avoid using salbutamol as a tocolytic since it may precipitate DKA
- Intrapartum
- Postpartum
- Significant decline in insulin requirements, especially for Type 2 diabetes
- Resume pre-pregnancy regimens
- 24-hour urine creatinine and protein in women with significant renal disease at 6 weeks postpartum
- Repeat ophthalmologic exam, which is compared to baseline at 12 – 14 weeks postpartum
- For contraceptives:
- Combined oral contraceptives are contraindicated due to the increased risk of thromboembolism, stroke and coronary artery disease
- Progestogen-only contraceptives can be used in women without vascular disease
- Intrauterine devices are safe to use
- Preconception:
- Complications
- Obstetrics
- Polyhydramnios
- Pre-eclampsia and eclampsia
- Spontaneous abortion
- Infection
- Postpartum haemorrhage
- Diabetic emergencies
- Hypoglycemia
- DKA
- Diabetic coma
- Vascular/end-organ involvement
- Nephropathy
- Neuropathy
- Retinopathy
- Cardiac
- Gastroenteropathy
- Fetal complications
- Fetal Macrosomia which leads to traumatic delivery, shoulder dystocia, and Erb’s palsy
- Unexplained fetal demise
- Congenital malformations
- Congenital Heart Defects. The most common malformations are transposition of the great arteries, ventricular septal defect, coarctation of the aorta, patent ductus arteriosus and cardiomegaly Most common malformations
- Anal atresia or rectal atresia
- Neural tube defects (excluding anencephaly)
- Caudal regression (pathognomic)
- Renal anomalies, e.g., ureteral duplication, renal agenesis, and cystic kidneys
- Situs inversus
- Intrauterine growth restrictions
- Single umbilical artery
- Polycythemia
- Delayed organ maturation
- Neonatal complications
- Preterm birth
- Respiratory distress
- Hypoglycemia
- Hypocalcaemia
- Hyperbilirubinemia
- Hypertrophic cardiomyopathy (can progress to CHF, common with macrosomia)
- Obstetrics
- Precipitating factors for DKA in Pregnancy
- Hyperemesis gravidarum
- Use of B-sympathomimetic drugs for tocolysis
- Infections
- Use of corticosteroids to induce fetal lung maturity
Capillary blood glucose goal in pregestational diabetes
| Specimen | Blood glucose (mmol/L) |
|---|---|
| Fasting | 3.3-5.0 |
| Premeal | 3.3-5.8 |
| Postprandial 1h | < 7.8 |
| Postprandial 2h | < 6.7 |
| Overnight (0200-0600h ) | 3.3-6.7 |
Adverse outcomes are associated with poor pre-pregnancy and early pregnancy HbA1C levels
| HbA1C | Risk of congenital malformations |
|---|---|
| < 7% | 3% risk |
| 7-9% | 14% risk |
| 9-11% | 23% risk |
| > 12% | 25% risk |