Preexisting Diabetes in Pregnancy

Background

• Preexisting diabetes affects 1% of all pregnancies and includes women known to have diabetes before pregnancy or who meet the diagnostic criteria at the initial prenatal visit.
• Poor glycemic control in early pregnancy is associated with adverse maternal outcomes including preeclampsia, preterm delivery, cesarean section, and maternal mortality.
• Poor glycemic control in early pregnancy is associated with adverse fetal outcomes including congenital malformations, perinatal mortality, and macrosomia (which affects 45% of affected infants).

Evaluation

• All women with preexisting type 1 or type 2 diabetes should receive preconception care to optimize glycemic control and assess for complications.
  • Patients should have their HbA1c measured and should be evaluated for underlying vasculopathy, including a retinal exam by an ophthalmologist, a 24-hour urine collection for protein excretion and creatinine clearance, lipid assessment, and electrocardiography.
  • Patients with type 1 diabetes should have evaluation of thyroid function.
• Daily fasting, preprandial, and postprandial self-monitoring of blood glucose (preferably with the fingerstick method) recommended throughout pregnancy to achieve glycemic control (Strong recommendation).
• Other testing throughout pregnancy
  • First trimester evaluations should include routine prenatal testing, measurement of HbA1c, thyroid-stimulating hormone in women with type 1 diabetes, a 24-hour urine collection for protein excretion and creatinine clearance if not obtained prior to conception, and electrocardiogram. Patients should be referred for evaluation by ophthalmologist, dietician, endocrinologist, cardiologist, and/or nephrologist as needed.
  • Second trimester evaluations include ultrasound with detailed anatomical survey and fetal echocardiography if cardiac defects are suspected or when the fetal heart and great vessels cannot be visualized adequately by routine anatomical ultrasonography, or in patients at increased risk of cardiac anomalies, such as in those with elevated HbA1c.
  • Third trimester evaluations include assessment of fetal growth, and antenatal fetal surveillance, including nonstress testing, biophysical profile, or the modified biophysical profile once or twice per week.

Management

• Develop or adjust a management plan to achieve near-normal glycemia, while minimizing significant hypoglycemia (Strong recommendation).
• The optimal intensity of glycemic control is unclear but loose control is associated with increased rates of some adverse maternal and fetal outcomes.
• Provide individualized medical nutrition therapy (MNT) as needed to achieve treatment goals (preferably by a registered dietitian familiar with MNT for diabetes and pregnancy) (Strong recommendation).
• The benefits of appropriate daily physical activity should be emphasized (Strong recommendation).
• Best results for optimal glycemic control are usually obtained with intensified insulin regimens (Strong recommendation).
• Regimens of multiple doses of subcutaneous long- and short-acting insulins and continuous subcutaneous insulin infusion may similarly improve maternal or fetal outcomes.
• Limit and individualize use of oral antidiabetic agents for control of type 2 diabetes mellitus during pregnancy until data regarding safety and efficacy become available.