What precautions, targets, and pre-pregnancy medications should be prescribed for a 29-year-old female with a 12-year history of Type 1 Diabetes Mellitus (T1DM), Body Mass Index (BMI) of 26, Hemoglobin A1c (HbA1c) of 6.9, on a basal-bolus insulin regimen, no diabetic retinopathy, normal estimated Glomerular Filtration Rate (eGFR), and a vitamin D level indicating deficiency?

Preconception Management for T1DM

Your patient requires immediate optimization before conception, with a target A1C <6.5% (ideally <6%), discontinuation of any teratogenic medications, vitamin D supplementation, high-dose folic acid, comprehensive screening for diabetic complications, and strict contraception until metabolic goals are achieved. 1

Immediate Medication Review and Adjustments

Medications to Discontinue NOW

• Stop ACE inhibitors and ARBs immediately if she is taking any, as these are teratogenic and associated with fetal renal anomalies, oligohydramnios, and fetal death 1, 2
• Stop statins immediately if prescribed, as they are pregnancy category X and contraindicated 1, 2

Insulin Management

• Continue basal-bolus insulin regimen as insulin is the only acceptable pharmacologic agent for T1DM in pregnancy 2, 3
• Expect insulin requirements to decrease in first trimester due to enhanced insulin sensitivity, then increase exponentially in second and third trimesters, potentially doubling by the third trimester 3, 4
• Plan for weekly dose adjustments starting at 16 weeks gestation 3

Blood Pressure Management (if applicable)

• Switch to methyldopa, labetalol, or long-acting nifedipine if she requires antihypertensive therapy 1
• Target blood pressure 110-135/85 mmHg 1

Glycemic Targets for Preconception Period

A1C Goals

• Target A1C <6.5% before conception, ideally as close to 6% as possible without significant hypoglycemia 1, 2, 5
• Her current A1C of 6.9% is too high for safe conception and requires optimization 1, 6
• The risk of diabetic embryopathy (anencephaly, microcephaly, congenital heart disease) increases directly with A1C elevations, particularly during the critical 5-8 week organogenesis period when most women don't yet know they're pregnant 2, 1

Daily Glucose Targets (Start Now)

• Fasting: 70-95 mg/dL 2, 3
• Preprandial: 60-99 mg/dL 2
• 1-hour postprandial: 110-140 mg/dL 2, 3
• 2-hour postprandial: 100-120 mg/dL 2, 3

Monitoring Requirements

• Self-monitoring of blood glucose 4-6 times daily minimum (fasting, preprandial, and postprandial) 3
• Consider continuous glucose monitoring (CGM) to improve glucose control and reduce hypoglycemia risk 3
• Monthly A1C monitoring during preconception optimization 2

Essential Supplementation

Folic Acid

• Prescribe prenatal vitamins with at least 400 mcg folic acid immediately, ideally 400-800 mcg 1, 2
• Must be started before conception to minimize risk of fetal malformations 4, 7

Vitamin D

• Her vitamin D level of 21 ng/mL indicates deficiency (normal >30 ng/mL)
• Supplement with vitamin D to achieve normal levels before conception 1
• Typical dosing: 1000-2000 IU daily or higher based on degree of deficiency

Potassium Iodide

• 150 mcg potassium iodide in prenatal vitamin 1

Comprehensive Screening for Diabetic Complications

Ophthalmologic Evaluation

• Dilated eye examination immediately before conception 2, 1
• Even though she has no retinopathy currently, pregnancy increases risk of development and/or progression of diabetic retinopathy 2
• Plan for repeat dilated eye exams every trimester during pregnancy and 1-year postpartum 2

Renal Function Assessment

• Her eGFR is normal, but obtain baseline urine albumin-to-creatinine ratio 2, 1
• Serum creatinine 2, 1
• Women with diabetic nephropathy have increased risk of preeclampsia and preterm delivery, though pregnancy doesn't worsen kidney function if baseline creatinine is normal 4

Additional Laboratory Testing

• Thyroid-stimulating hormone (TSH) to screen for thyroid dysfunction 2, 1
• Rubella immunity, rapid plasma reagin, hepatitis B, HIV testing 2
• Pap smear and cervical cultures 2
• Blood typing 2

Cardiovascular Assessment

• Screen for diabetic neuropathy including autonomic neuropathy 1
• Assess for hypertension and optimize control before conception 1

Contraception Until Optimization

Prescribe effective contraception immediately and use until A1C <6.5% is achieved 1, 2

• This is non-negotiable given the direct relationship between periconceptional hyperglycemia and congenital malformations 2, 1
• The critical organogenesis window (5-8 weeks) occurs before most women know they're pregnant 1

Multidisciplinary Care Coordination

Refer to multidisciplinary preconception clinic including: 1, 5

• Endocrinologist or diabetologist
• Maternal-fetal medicine specialist
• Registered dietitian nutritionist
• Diabetes educator
• Ophthalmologist

Medical Nutrition Therapy

• Referral to registered dietitian to establish food plan, insulin-to-carbohydrate ratios, and weight gain goals 2
• Consistent carbohydrate intake is essential to match insulin dosing and avoid hyperglycemia or hypoglycemia 2
• Her BMI of 26 (overweight) requires counseling on appropriate gestational weight gain targets

Critical Pitfalls to Avoid

Hypoglycemia Risk

• Severe hypoglycemia risk increases significantly during pregnancy, particularly in first trimester and during intensive glycemic control 4, 5
• Early warning symptoms may be blunted with long diabetes duration (she has 12 years) 8
• Educate on recognition and management of hypoglycemia 2

Unplanned Pregnancy

• 50% of pregnancies in women with diabetes are unplanned, leading to poor outcomes 1
• Emphasize that achieving optimal control before conception is the single most important intervention to reduce congenital anomalies 1, 6

Timing of Conception

• Do not attempt conception until A1C <6.5% is documented 1
• This may take 3-6 months of intensive management 5

Timeline for Pregnancy Planning

1. Immediate (Today): Start folic acid, vitamin D supplementation, review/stop teratogenic medications, prescribe contraception, order comprehensive screening labs and dilated eye exam 2, 1

2. Within 1-2 weeks: Establish multidisciplinary care, intensify insulin regimen to achieve tighter glucose targets, initiate CGM if available 1, 3

3. Monthly: Monitor A1C, adjust insulin doses, reinforce glucose monitoring and dietary adherence 2

4. When A1C <6.5%: Discontinue contraception and attempt conception 1

5. Once pregnant: Transition to even stricter targets (A1C <6%, fasting <95 mg/dL, 1-hour postprandial <140 mg/dL) 2