Diabetes Management During Breastfeeding

Medication Safety and Recommendations

Insulin is the safest and most preferred medication for diabetes management during breastfeeding, as it does not cross into breast milk in measurable amounts, and all types of insulin can be safely used by breastfeeding women 1, 2, 3
Metformin is generally considered safe during breastfeeding, but with some caveats, including limited long-term safety data, and is excreted into breast milk in small amounts, with a mean infant exposure of approximately 0.28-1.08% of the weight-normalized maternal dose 2, 3
Glyburide and glipizide can be safely used by breastfeeding women, according to the American Academy of Pediatrics and other guideline societies, which have recommended these sulfonylureas as preferred oral hypoglycemic agents during breastfeeding 2
The American College of Obstetricians and Gynecologists and other guideline societies recommend insulin as the first-line treatment for breastfeeding mothers with diabetes, due to its safety profile and lack of concerns about infant exposure or long-term effects on offspring 2, 3

Breastfeeding mothers on insulin should ensure adequate carbohydrate intake to prevent hypoglycemia, and monitor their glucose levels regularly using methods specific for glucose, as recommended by the American Diabetes Association and other guideline societies 2, 3
Regular glucose monitoring is essential for breastfeeding mothers with diabetes, regardless of treatment approach, to ensure optimal blood glucose control and prevent complications, as recommended by the American Diabetes Association and other guideline societies 3
Metformin dosing should be timed to minimize peak concentrations during breastfeeding when possible, to reduce the risk of infant exposure, and insulin doses will likely need to be reduced compared to pre-pregnancy requirements due to the glucose-lowering effect of breastfeeding, as recommended by the American College of Obstetricians and Gynecologists and other guideline societies 2
The initial approach to managing GDM involves lifestyle modifications, including medical nutrition therapy, regular physical activity, weight management, and blood glucose monitoring with specific targets: fasting glucose <95 mg/dL, one-hour postprandial glucose <140 mg/dL, or two-hour postprandial glucose <120 mg/dL, as recommended by the American Diabetes Association 3, 4

Insulin is the preferred first-line medication for treating hyperglycemia in gestational diabetes mellitus (GDM) when lifestyle modifications are insufficient to achieve glycemic targets, as recommended by the American Diabetes Association 3, 4, 5, 6
Insulin does not cross the placenta to a measurable extent, ensuring no concerns about fetal exposure or long-term effects on offspring 5
Insulin has been demonstrated to improve perinatal outcomes in randomized studies, with the ability to be titrated precisely to achieve glycemic targets 6
Initially, a small proportion of the total daily dose should be given as basal insulin, and a greater proportion as prandial insulin, with frequent titration necessary due to changing insulin requirements throughout pregnancy 7

Metformin may be considered in women who cannot use insulin safely due to cost, language barriers, or cultural influences, but this should only be after discussing the known risks and need for more long-term safety data, as noted by the Society for Maternal-Fetal Medicine 3, 8
Sulfonylurea (glyburide) crosses the placenta and is associated with higher rates of neonatal hypoglycemia and macrosomia than insulin, and failed to be found non-inferior to insulin based on composite neonatal outcomes 6
Metformin may have long-term safety concerns for offspring, including higher BMI and increased obesity at various follow-up points, although the strength of evidence for these concerns is not specified 6, 4, 9

Patients should be informed that metformin crosses the placenta and long-term safety data is lacking, and oral agents should not be used without informed consent 10, 5
Regular blood glucose monitoring is essential regardless of treatment approach, and delayed insulin initiation should be avoided as poor glycemic control increases risks of adverse maternal and fetal outcomes 4, 3
Insulin, not metformin, is the preferred treatment for patients with a history of gestational diabetes who are pregnant again, especially during the first trimester 4, 3, 6