Which long‑acting insulins are safe for use during pregnancy?

Long-Acting Insulins Safe for Use in Pregnancy

Insulin detemir and insulin glargine are both safe long-acting insulins that can be used during pregnancy, with insulin detemir being FDA-approved for this indication while insulin glargine can be continued if already successfully used preconceptionally. 1

Primary Recommendations

First-Line Long-Acting Insulins

Insulin Detemir:

• FDA-approved for use during pregnancy
• May be initiated during pregnancy for women requiring basal insulin, particularly when NPH insulin causes problematic hypoglycemia 1
• Can be continued in women already successfully using it before pregnancy 1
• Associated with lower rates of nocturnal hypoglycemia compared to NPH insulin 1

Insulin Glargine:

• NOT FDA-approved for pregnancy, but widely used with evidence of safety 1
• Can be continued during pregnancy in women successfully using it preconceptionally 1
• Should be discussed with patients regarding lack of FDA approval and theoretical mitogenicity concerns 1
• May be replaced by insulin detemir or NPH insulin if concerns exist 1

Alternative Basal Insulin

NPH Insulin:

• Traditional option that remains acceptable
• Less expensive than long-acting analogs 1
• Higher rates of nocturnal hypoglycemia compared to detemir or glargine 1

Clinical Decision Algorithm

For women already on long-acting insulin before pregnancy:

1. If on insulin detemir → Continue without change 1
2. If on insulin glargine → Discuss FDA approval status and theoretical risks; may continue if well-controlled OR switch to detemir/NPH 1

For women initiating basal insulin during pregnancy:

1. First choice: Insulin detemir (FDA-approved) 1
2. Alternative: NPH insulin (if cost is prohibitive or detemir unavailable)
3. Insulin glargine: May be used but requires informed discussion about off-label use 1

Important Caveats

Newer Long-Acting Insulins

• Insulin degludec: Not yet established as safe for pregnancy in guidelines, though emerging research suggests potential safety 2, 3
• Requires more data before routine recommendation
• The 2013 Endocrine Society guidelines (the most comprehensive guideline evidence provided) do not address degludec as it was not widely available at that time

Key Safety Considerations

Both detemir and glargine:

• Reduce nocturnal hypoglycemia compared to NPH 1
• Have evidence of safety during pregnancy from observational studies 1
• More expensive than NPH insulin 1
• Should be part of multiple daily dose regimen or continuous subcutaneous insulin infusion for optimal flexibility 1

Practical Implementation:

• Changes to insulin regimens should occur well before conception when possible 1
• Allows time for optimization and patient expertise development
• Frequent titration needed throughout pregnancy due to changing insulin requirements 4

Strength of Evidence

The Endocrine Society 2013 guidelines 1 provide the strongest guideline-level evidence, with consistent recommendations across multiple excerpts. These are augmented by the 2025 ADA Standards of Care 4 and 2025 Endocrine Society/European Society joint guideline 5, which support insulin as the backbone of diabetes treatment in pregnancy.

The recommendation for detemir and glargine is graded as 2QQEE (weak recommendation, very low-quality evidence) in the Endocrine Society guidelines 1, reflecting that while both are widely used and appear safe, randomized controlled trial data specifically in pregnancy remains limited 6, 7.