Management of Diabetes in Pregnancy
Insulin is the preferred treatment for all types of diabetes in pregnancy, with strict glycemic targets of fasting glucose <95 mg/dL and either 1-hour postprandial <140 mg/dL or 2-hour postprandial <120 mg/dL, aiming for A1C <6% if achievable without significant hypoglycemia 1.
Glycemic Targets and Monitoring
The 2025 ADA Standards establish clear, non-negotiable glucose thresholds that differ by diabetes type:
For Type 1 and Type 2 Diabetes:
- Fasting: 70-95 mg/dL (3.9-5.3 mmol/L)
- 1-hour postprandial: 110-140 mg/dL (6.1-7.8 mmol/L)
- 2-hour postprandial: 100-120 mg/dL (5.6-6.7 mmol/L)
For Gestational Diabetes (GDM):
- Fasting: <95 mg/dL (<5.3 mmol/L)
- 1-hour postprandial: <140 mg/dL (<7.8 mmol/L)
- 2-hour postprandial: <120 mg/dL (<6.7 mmol/L) 1
A1C Goals
Target A1C <6% (<42 mmol/mol) during pregnancy if achievable without significant hypoglycemia; relax to <7% (<53 mmol/mol) if necessary to prevent hypoglycemia 1. This recommendation is based on observational data showing A1C <6-6.5% in early gestation correlates with the lowest rates of adverse fetal outcomes, large-for-gestational-age infants, preterm delivery, and preeclampsia 1.
Critical caveat: A1C is a secondary measure in pregnancy due to increased red blood cell turnover causing physiologically lower values, and it fails to capture postprandial hyperglycemia that drives macrosomia 1.
Monitoring Strategy
Use continuous glucose monitoring (CGM) for Type 1 diabetes in pregnancy to achieve glycemic goals including time in range and time above range 1. CGM may benefit other diabetes types in pregnancy 1. However, do not replace standard pregnancy glucose targets (fasting <95 mg/dL, 1-hour postprandial <140 mg/dL, 2-hour postprandial <120 mg/dL) with a single 24-hour CGM target <140 mg/dL, as this approach lacks evidence and may miss critical fasting hyperglycemia 2.
For Type 2 diabetes, either CGM or self-monitoring of blood glucose (SMBG) is acceptable, though CGM shows promise based on indirect evidence from non-pregnant populations and Type 1 diabetes pregnancy data 2.
Insulin Therapy
Type 1 Diabetes
Insulin is mandatory for Type 1 diabetes management in pregnancy 3. Both multiple daily injections (MDI) and continuous subcutaneous insulin infusion (CSII/pump therapy) are reasonable, with neither proven superior 3.
Hybrid closed-loop (HCL) insulin delivery systems are recommended over standard pump therapy or MDI with CGM 2. The CamAPS FX is the only FDA-approved automated insulin delivery (AID) system for pregnancy 4. Meta-analysis demonstrates HCL increases time in range by 3.81% (an additional 2.5 hours/day) and reduces time below range 2. The MiniMed 780G, though not pregnancy-approved, showed 24 minutes more overnight time in pregnancy range with less hypoglycemia 4.
Important limitation: Current FDA-approved AID systems lack pregnancy-specific algorithms 3. Continue or initiate AID only in carefully selected patients with expert guidance, assessing glycemic levels, hypoglycemia history, technology comfort, psychosocial factors, and cost 3. Predictive low-glucose suspend (PLGS) technology may be particularly suited for pregnancy as suspension thresholds align with premeal and overnight pregnancy targets 3.
Type 2 Diabetes
Insulin is the preferred agent for Type 2 diabetes in pregnancy 3. Optimal glycemic goals are often easier to achieve than in Type 1 diabetes but may require much higher insulin doses, sometimes necessitating concentrated formulations 3.
Do not routinely add metformin to insulin in pregnant patients with Type 2 diabetes already on insulin 2. While one RCT showed less maternal weight gain, fewer cesarean births, and fewer macrosomic neonates with metformin addition, there was a doubling of small-for-gestational-age infants 3. Additionally, avoid metformin in pregnant patients with hypertension, preeclampsia, or those at risk for intrauterine growth restriction due to potential for growth restriction or acidosis with placental insufficiency 3.
Hypoglycemia Management
Type 1 diabetes patients face increased hypoglycemia risk in the first trimester with altered counter-regulatory responses decreasing hypoglycemia awareness 3. Provide education on prevention, recognition, and treatment to patients and family members before, during, and after pregnancy 3. Remember that insulin resistance drops rapidly with placental delivery 3.
Nutrition Management
Either a carbohydrate-restricted diet (<175 g/day) or usual diet (>175 g/day) is acceptable during pregnancy 2. The evidence is insufficient to mandate a specific carbohydrate threshold, reflecting very low certainty data 2.
For Type 2 diabetes with obesity, recommended weight gain is 15-25 lb (6.8-11.3 kg) for overweight patients and 10-20 lb (4.5-9.1 kg) for those with obesity 3. Do not recommend weight loss during pregnancy due to increased risk of small-for-gestational-age infants 3.
Preconception and Delivery Planning
Preconception Care
Screen for pregnancy intention at every reproductive, diabetes, and primary care visit (and urgent care/emergency visits when appropriate) 2. Strong indirect evidence links preconception care with reduced first-trimester A1C and congenital malformations 2.
Use contraception when pregnancy is not desired 2. For patients on GLP-1 receptor agonists, discontinue before conception rather than waiting until pregnancy is confirmed, given limited safety data 2.
Refer for comprehensive eye exam before pregnancy 1. Patients with preexisting diabetic retinopathy require close monitoring during pregnancy, as rapid euglycemia implementation can worsen retinopathy 3.
Delivery Timing
Plan early delivery based on risk assessment rather than expectant management 2. Indirect evidence suggests risks may outweigh benefits of expectant management beyond 38 weeks gestation 2. For diet-controlled GDM, spontaneous labor is acceptable without obstetric indications, but induce at term for insulin-treated GDM or poor glycemic control 5.
Postpartum Care
Provide postpartum endocrine care (diabetes management) in addition to usual obstetric care 2. This is critical as the postpartum period overlaps with potential preconception for future pregnancies 2.
Technology Considerations
Emerging evidence supports AID systems maintaining glycemic goals during delivery and postpartum with lower hypoglycemia risk 4. However, more systems with flexible pregnancy-range glucose targets and algorithms adapting to changing insulin requirements are needed 4.