Best Insulin for Pregnancy with Diabetes
Insulin is the preferred treatment for both type 1 and type 2 diabetes during pregnancy, with either multiple daily injections or insulin pump technology being appropriate options for achieving glycemic control. 1
Insulin Selection for Different Types of Diabetes
Type 1 Diabetes
- Insulin is the only appropriate therapy for type 1 diabetes in pregnancy 1
- Either multiple daily injections or insulin pump technology can be used 1
- Insulin resistance increases significantly in the second and third trimesters, requiring frequent dose adjustments 2
- Insulin requirements often drop by 9-18% between weeks 7-15 of gestation 2
Type 2 Diabetes
- Insulin is the preferred agent for managing type 2 diabetes in pregnancy 1
- May require higher doses than in type 1 diabetes, sometimes necessitating concentrated insulin formulations 1
- An RCT of metformin added to insulin for type 2 diabetes showed less maternal weight gain and fewer cesarean births, but doubled the rate of small-for-gestational-age neonates 1
Gestational Diabetes
- Lifestyle changes are the first-line approach for gestational diabetes 1
- When lifestyle modifications are insufficient, insulin is the preferred pharmacological treatment 1, 3
- Oral agents (metformin, glyburide) are not recommended as first-line treatments as they cross the placenta 1
Insulin Types and Safety in Pregnancy
Short-Acting Insulin Analogues
- Insulin lispro and insulin aspart are considered safe in pregnancy 4, 5
- These analogues have been reclassified from FDA pregnancy category C to category B 5
- May improve post-prandial glycemic control in women with type 1 diabetes 4
- Do not cross the placental barrier 6
Long-Acting Insulin Analogues
- Insulin detemir has the strongest evidence base among long-acting analogues 4, 5
- A head-to-head comparison between insulin detemir and NPH insulin showed improved fasting plasma glucose with insulin detemir without increased hypoglycemia 4
- For insulin glargine, most studies are small and retrospective, but no major safety concerns have been reported 5
- Insulin lispro protamine suspension (ILPS) appears to be at least as safe and effective as NPH insulin based on retrospective analyses involving >1200 pregnant women 6
Glycemic Targets and Monitoring
Target blood glucose levels during pregnancy 2:
- Fasting: 70-95 mg/dL
- 1-hour postprandial: 110-140 mg/dL
- 2-hour postprandial: 100-120 mg/dL
- A1C target <6% if achievable without significant hypoglycemia
Frequent blood glucose monitoring is essential due to changing insulin requirements throughout pregnancy 1
Special Considerations
- Hypoglycemia risk is increased in the first trimester, and pregnant women have altered counter-regulatory responses that may decrease hypoglycemia awareness 1, 2
- Insulin requirements drop dramatically after delivery of the placenta 1, 2
- Pregnant women with diabetes should be prescribed low-dose aspirin 100-150 mg/day starting at 12-16 weeks gestation to reduce preeclampsia risk 1
- Regular eye exams are recommended due to potential worsening of retinopathy during pregnancy 1, 2
Insulin Delivery Methods
- Both multiple daily injections and insulin pump technology are reasonable delivery strategies 1
- Predictive low-glucose suspend (PLGS) technology may be better than sensor-augmented insulin pumps for reducing low glucose values 1
- Current hybrid closed-loop insulin pump systems approved by the FDA do not achieve pregnancy targets 1
Practical Approach to Insulin Management
- Start with appropriate insulin type based on diabetes classification
- Adjust insulin regimen based on frequent blood glucose monitoring
- Anticipate changing insulin requirements throughout pregnancy
- Be prepared for rapid decrease in insulin requirements after delivery
- Provide education about hypoglycemia prevention, recognition, and treatment
The complexity of insulin management in pregnancy underscores the importance of referral to specialized centers offering team-based care when available 1.