Which Insulin Should Not Be Given to Pregnant People
Insulin glulisine should not be used in pregnancy due to complete absence of safety data, and insulin degludec should also be avoided as it has not been studied in pregnant populations. 1, 2, 3, 4
Insulins to Avoid
Insulin Glulisine
- There are no published reports or controlled trials of insulin glulisine use in pregnancy, making its use not recommended. 1, 2, 3, 4
- The American Diabetes Association guidelines note that glulisine is labeled as pregnancy category C (under the old classification system), reflecting insufficient safety data. 5
Insulin Degludec
- Insulin degludec has not been studied in pregnancy and should be avoided. 3, 4
- No controlled trials or safety data exist for this ultra-long-acting insulin analog in pregnant populations. 3, 4
Insulins with Limited Data (Use with Caution)
Insulin Glargine
- While glargine is labeled pregnancy category C, retrospective studies of approximately 335 pregnancies show no increased incidence of congenital malformations compared to human insulin. 2
- Most studies are small and retrospective, but no major safety concerns have been reported. 1, 3
- It appears reasonable to continue insulin glargine if required to achieve excellent glycemic control, but it should not be initiated as first-line therapy in pregnancy. 1
- One case-control study found a higher frequency of femoral length <50th centile and large-for-gestational-age infants with glargine use, though this was a small retrospective study. 6
Preferred Insulin Options in Pregnancy
Rapid-Acting Analogs (Safe and Recommended)
- Insulin lispro and insulin aspart are safe in pregnancy and have been reclassified from category C to category B by the FDA. 3, 4
- These improve postprandial glycemic control in women with type 1 diabetes without adverse maternal or fetal effects. 1, 2
Long-Acting Analogs
- Insulin detemir is the preferred first-line long-acting analog in pregnancy, with FDA reclassification to category B. 3, 4
- A head-to-head comparison showed improved fasting plasma glucose with detemir versus NPH insulin without increased hypoglycemia, though fetal outcomes did not differ. 1
Human Insulin
- None of the currently available human insulin preparations cross the placenta, making them safe alternatives. 7
- NPH insulin remains a reasonable option, particularly for women already well-controlled on this regimen. 1
Key Clinical Considerations
- Insulin is the preferred agent for management of both type 1 and type 2 diabetes in pregnancy. 7
- Insulins studied in randomized controlled trials are preferred over those studied only in cohort studies or case reports. 7
- Pregnant individuals require frequent insulin dose adjustments due to changing insulin resistance throughout pregnancy, with requirements often doubling by the third trimester. 5
- Referral to specialized team-based care is recommended when available due to the complexity of insulin management in pregnancy. 7