For rats and rabbits, dosed at 50 and 10 times the human subcutaneous dose during organogenesis, respectively, the effects of insulin glargine did not differ greatly from those observed with regular human insulin. In rabbits, 5 fetuses from 2 high-dosed litters exhibited dilation of the cerebral ventricles. Fertility and early embryonic development appeared normal. In published human pregnancy reports, no specific adverse effects of insulin glargine on pregnancy and no specific malformations nor fetal or neonatal toxicity has been reported. These studies are not definitive in ruling out the absence of risk due to methodological limitations. The estimated background risk of major birth defects in women with pregestational diabetes with an HbA1c greater than 7 is 6% to 10%; in women with a HbA1c greater than 10, it has been reported to be as high as 20% to 25%. There are no controlled data in human pregnancy.

Clinical Considerations:
-Poorly controlled diabetes during pregnancy increases the maternal risk for diabetic ketoacidosis, preeclampsia, spontaneous abortions, preterm delivery, and delivery complications.
-Poorly controlled diabetes during pregnancy increases the fetal risk for major birth defects, stillbirth, and macrosomia related morbidity.

AU TGA pregnancy category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

Use during pregnancy only if the potential benefit justifies the potential risk to the fetus

AU TGA pregnancy category: B3
US FDA pregnancy category: Not assigned

Risk Summary: Published studies of insulin glargine use during pregnancy have not reported a clear association with adverse developmental outcomes; there are risks to the mother and fetus associated with poorly controlled diabetes in pregnancy.

Comments:
-Patients with diabetes or a history of gestational diabetes should maintain good metabolic control before conception and during pregnancy. Insulin requirements may decrease during the first trimester; generally increase during the second and third trimesters, and rapidly decline after delivery. Careful monitoring of glucose control is essential.

See references

Use is considered acceptable; caution is recommended.

Excreted into human milk: Yes

Comments: Women who are breastfeeding may require adjustments in insulin dose and diet.

Exogenous insulins, including the newer biosynthetic insulins (i.e. aspart, detemir, glargine, glulisine, lispro) appear to be excreted into breast milk. Insulin is a protein that is inactivated if taken by mouth. If absorbed, it would be destroyed in the digestive tract of the infant.

Lactation onset occurs later in women with type 1 diabetes, and there is an even greater delay in those with poor glucose control. However, once established lactation persists. Insulin requirements are generally lower in women who breastfeed, most likely due to glucose being used for milk production.

See references