What is the preferred insulin therapy, Lantus (insulin glargine) or Degludec (insulin degludec), for managing diabetes in pregnancy?

Insulin Therapy in Pregnancy: Lantus vs Degludec

Insulin is the preferred agent for management of both type 1 and type 2 diabetes in pregnancy, with NPH insulin and insulin glargine (Lantus) being established safe options, while insulin degludec lacks sufficient safety data for use during pregnancy. 1, 2

Insulin as First-Line Therapy in Pregnancy

• Insulin is consistently recommended as the preferred agent for managing both type 1 and type 2 diabetes during pregnancy by major guidelines including the American Diabetes Association 1
• None of the currently available human insulin preparations, including NPH insulin, have been demonstrated to cross the placenta, making them safe options for pregnant patients 2
• Both multiple daily insulin injections and continuous subcutaneous insulin infusion are reasonable delivery strategies during pregnancy 1

Safety Considerations for Insulin Glargine (Lantus) in Pregnancy

• Trans-placental transfer studies show that insulin glargine does not cross the placenta when used at therapeutic concentrations 3
• While there are no randomized controlled trials on insulin glargine in pregnancy, observational studies have not associated its use with adverse maternal or neonatal outcomes 3
• Insulin glargine can be safely continued during pregnancy in women who were taking it prior to pregnancy and have achieved good glycemic control 3

Insulin Degludec in Pregnancy

• Current guidelines and evidence do not specifically address the safety of insulin degludec in pregnancy 1
• None of the current automated insulin delivery systems (which might use degludec) approved by the FDA have algorithms set to achieve pregnancy goals 1
• The lack of specific safety data for degludec in pregnancy makes it a less preferred option compared to insulin glargine or NPH insulin 2

Physiological Considerations for Insulin Management in Pregnancy

• Early pregnancy is characterized by enhanced insulin sensitivity and lower glucose levels, which may require lower insulin doses 2
• Insulin requirements typically increase linearly from around 16 weeks, often doubling compared to pre-pregnancy needs 2
• Insulin requirements drop rapidly with delivery of the placenta 1, 2
• Pregnant individuals with type 1 diabetes have an increased risk of hypoglycemia in the first trimester due to altered counter-regulatory responses 1, 2

Practical Approach to Insulin Selection in Pregnancy

• For patients already on insulin glargine (Lantus) with good glycemic control, it is reasonable to continue this therapy during pregnancy 3
• For patients requiring initiation of insulin during pregnancy, NPH insulin or insulin glargine would be preferred over insulin degludec due to more established safety data 2
• Frequent blood glucose monitoring and insulin dose adjustments are necessary throughout pregnancy due to changing insulin requirements 2
• Glycemic targets during pregnancy include fasting glucose of 70–95 mg/dL and one-hour postprandial glucose of 110–140 mg/dL 2

Caveats and Special Considerations

• Pregnancy is a ketogenic state, and women with diabetes are at risk for diabetic ketoacidosis at lower blood glucose levels than in the non-pregnant state 1
• Education about hypoglycemia prevention, recognition, and treatment is essential for pregnant patients using insulin and their family members 2
• Pregnant individuals with diabetes should be prescribed low-dose aspirin 100–150 mg/day starting at 12 to 16 weeks of gestation to lower the risk of preeclampsia 2
• Referral to a specialized center offering team-based care is recommended when available for pregnant individuals with diabetes 2