What are the management and treatment options for diabetes in pregnancy?

Management of Diabetes in Pregnancy

Women with diabetes in pregnancy require intensive glycemic control with insulin as first-line therapy, targeting fasting glucose <95 mg/dL and 1-hour postprandial <140 mg/dL, with preconception A1C <6.5% to minimize congenital malformations and adverse maternal-fetal outcomes. 1

Preconception Planning and Optimization

All women of childbearing age with diabetes must receive preconception counseling to achieve near-euglycemia before pregnancy, as organogenesis occurs at 5-8 weeks gestation when many women don't yet know they're pregnant 1. The risk of diabetic embryopathy—including anencephaly, microcephaly, congenital heart disease, and caudal regression—is directly proportional to A1C elevations during the first 10 weeks 1.

Preconception Glycemic Targets

• Target A1C <6.5% (48 mmol/mol) before conception to achieve the lowest risk of congenital anomalies, preeclampsia, and preterm birth 1
• Effective contraception must be prescribed and used until glycemic targets are achieved 1

Medication Review and Adjustments

• Immediately discontinue ACE inhibitors, angiotensin receptor blockers, and statins due to teratogenic risk 1
• Initiate folic acid supplementation at minimum 400 mg daily 1

Comprehensive Screening

• Diabetes-specific testing: A1C, creatinine, urinary albumin-to-creatinine ratio 1
• Thyroid-stimulating hormone (TSH) 1
• Comprehensive ophthalmologic examination for retinopathy assessment 1
• ECG in women ≥35 years with cardiac symptoms or risk factors 1

Multidisciplinary Team Approach

Ideally manage women in a multidisciplinary clinic including endocrinologist, maternal-fetal medicine specialist, registered dietitian nutritionist, and diabetes care and education specialist 1. Studies demonstrate improved outcomes when care is delivered by teams focused on glycemic control from preconception through pregnancy 1.

Glycemic Targets During Pregnancy

Blood Glucose Monitoring Targets

Fasting and postprandial self-monitoring of blood glucose is the primary tool for glycemic management 1:

• Fasting plasma glucose: <95 mg/dL (5.3 mmol/L) 1
• 1-hour postprandial: <140 mg/dL (7.8 mmol/L) 1
• 2-hour postprandial: <120 mg/dL (6.7 mmol/L) 1

These targets apply to both gestational diabetes mellitus (GDM) and preexisting diabetes 1. Postprandial monitoring is particularly important as it correlates with better glycemic control and lower risk of preeclampsia 1.

A1C Targets

• Optimal target: <6% (42 mmol/mol) if achievable without significant hypoglycemia 1
• Alternative target: <6.5% (48 mmol/mol) 1
• May relax to <7% (53 mmol/mol) if necessary to prevent hypoglycemia 1

A1C should be used as a secondary measure of glycemic control, not primary, because it doesn't fully capture postprandial hyperglycemia that drives macrosomia, and red blood cell turnover is increased in pregnancy 1. Monitor A1C monthly during pregnancy given these physiological changes 1.

Continuous Glucose Monitoring (CGM)

• CGM can be used as an adjunct to—but not a replacement for—self-monitoring of blood glucose 1
• When used with traditional monitoring, CGM reduces macrosomia and neonatal hypoglycemia in type 1 diabetes 1
• Do not use estimated A1C or glucose management indicator calculations from CGM in pregnancy 1

Insulin Management

Insulin as First-Line Therapy

Insulin is the preferred medication for managing both type 1 and type 2 diabetes in pregnancy because it does not cross the placenta to a measurable extent 1, 2. This is critical for fetal safety compared to oral agents that cross the placental barrier 1.

Insulin Delivery Methods

• Either multiple daily injections or insulin pump technology can be used in type 1 diabetes 1
• Physiologic basal-bolus regimens with rapid-acting insulin for meals and long-acting insulin for basal coverage are recommended 2
• Preprandial testing is recommended for women using insulin pumps or basal-bolus therapy to adjust premeal rapid-acting insulin dosage 1

Insulin Physiology Changes During Pregnancy

Understanding these changes is essential for dose adjustments 1, 2:

• Early pregnancy (first trimester): Increased insulin sensitivity, lower glucose levels, lower insulin requirements 1
• Second and early third trimester: Exponential increase in insulin resistance, insulin requirements may double 1, 2
• Late third trimester: Insulin resistance levels off 1
• Postpartum: Dramatic drop in insulin requirements immediately after placental delivery 1, 2

Insulin Dosing Adjustments

• Adjust insulin based on blood glucose monitoring results, carbohydrate intake, physical activity, and stage of pregnancy 2
• Regular evaluation of insulin requirements is necessary, typically every 2-3 weeks as pregnancy progresses 2
• A rapid reduction in insulin requirements may indicate placental insufficiency and requires immediate medical evaluation 2

Hypoglycemia Management

Women with type 1 diabetes have increased hypoglycemia risk in the first trimester and altered counterregulatory response throughout pregnancy 1. Education for patients and family members about prevention, recognition, and treatment of hypoglycemia is mandatory before, during, and after pregnancy 1, 2. Treat mild hypoglycemia immediately with fruit juice, sugar candies, or glucose tablets 3. Severe hypoglycemia may require glucagon injection or emergency medical services 3.

Diabetic Ketoacidosis (DKA) Prevention

Pregnancy is a ketogenic state, and women with type 1 diabetes are at risk for DKA at lower blood glucose levels than in the nonpregnant state 1. Women should be prescribed ketone strips and receive education on DKA prevention and detection 1. DKA carries a high risk of stillbirth 1. Women in DKA often require 10% dextrose with insulin drip to meet the higher carbohydrate demands of the placenta and fetus 1.

Management of Gestational Diabetes Mellitus (GDM)

Initial Lifestyle Management

Lifestyle change is an essential component of GDM management and may suffice for treatment of many women 1. Initial treatment includes 1:

• Medical nutrition therapy with individualized nutrition plan developed with a registered dietitian 1
• Minimum 175 g carbohydrate, 71 g protein, and 28 g fiber daily per Dietary Reference Intakes 1
• Physical activity and weight management 1
• Glucose monitoring targeting the same values as preexisting diabetes 1

Studies suggest 70-85% of women diagnosed with GDM can control it with lifestyle modification alone 1.

When to Add Medications

Medications should be added if glycemic targets are not achieved within 1-2 weeks of lifestyle intervention 1. Insulin remains the preferred first-line pharmacologic agent 1.

Oral Agents in GDM

While insulin is preferred, metformin and glyburide may be used in GDM, but both cross the placenta to the fetus (metformin likely crosses to a greater extent than glyburide) 1. Consider oral agents only in women who cannot use insulin safely or effectively due to cost, language barriers, comprehension, or cultural influences, after discussing known risks and need for more long-term safety data 1.

Medical Nutrition Therapy

Consistent carbohydrate intake is important to match insulin dosing and avoid glucose fluctuations 2. The food plan should provide adequate calories to promote fetal/neonatal and maternal health, achieve glycemic goals, and promote appropriate gestational weight gain 1.

Weight Gain Recommendations

• Overweight women: 15-25 lb 1
• Obese women: 10-20 lb 1
• No adequate data exists for optimal weight gain in women with BMI >35 kg/m² 1

Preeclampsia Prevention

Women with type 1 or type 2 diabetes should be prescribed low-dose aspirin 60-150 mg/day (usual dose 81 mg/day) by the end of the first trimester to lower the risk of preeclampsia 1. This recommendation is based on clinical trials and meta-analyses showing reduced morbidity and mortality 1.

Retinopathy Monitoring

Women with preexisting diabetic retinopathy need close monitoring during pregnancy to assess for progression and provide treatment if indicated 1. A critical caveat: rapid implementation of euglycemia in the setting of retinopathy is associated with worsening of retinopathy 1. Comprehensive ophthalmologic examination should occur at baseline and as needed throughout pregnancy 1.

Blood Pressure Management

In pregnancy complicated by diabetes and chronic hypertension, a target blood pressure of <135/85 mmHg is reasonable 1. Blood pressure targets lower than 120/80 mmHg may be associated with impaired fetal growth, especially with placental insufficiency 1.

Postpartum Management

Immediate Postpartum Period

Insulin requirements decrease dramatically after delivery of the placenta 1, 2. Close monitoring and rapid insulin dose adjustment are needed in the immediate postpartum period to prevent hypoglycemia 1, 2. Women should be counseled about significantly reduced insulin requirements for the initial few days postpartum 1.

Long-Term Follow-Up for GDM

Women with GDM have increased risk of developing type 2 diabetes in the future 4. Women with GDM should be tested for persistent diabetes or prediabetes at 4-12 weeks postpartum with a 75-g oral glucose tolerance test 5. After delivery, offer fasting plasma glucose at 6 weeks or A1C at 13 weeks to ensure GDM has resolved, followed by annual A1C 4.

Contraception Planning

A contraceptive plan should be discussed and implemented with all women with diabetes of reproductive potential 1. Family planning should include discussion of benefits of long-acting, reversible contraception 1.

Common Pitfalls to Avoid

• Never mix insulin with other insulin products 3
• Never use insulin in an insulin pump if the product is not approved for pump use 3
• Do not rely solely on A1C for glycemic management during pregnancy—prioritize self-monitoring of blood glucose 1
• Do not use CGM-derived estimated A1C or glucose management indicator in pregnancy 1
• Avoid rapid glycemic optimization in women with existing retinopathy without close ophthalmologic monitoring 1
• Do not continue ACE inhibitors, ARBs, or statins during pregnancy 1