New findings show that women who are breast feeding can be reassured that if they take metformin for Diabetes it won’t harm their baby.

Metformin is excreted into breast milk, but the levels are not enough to adversely affect blood sugar levels of nursing infants, according to the findings of a small study reported in the medical journal Obstetrics & Gynecology.

Gerald G. Briggs from Miller Children’s Hospital in Long Beach, California, and colleagues explain that metformin is occasionally used for controlling Type 2 diabetes in nursing mothers, but the effect of metformin on the baby has been unclear.

Diabetes Definition
Diabetes is a life-long disease marked by high levels of sugar in the blood. It can be caused by too little insulin (a hormone produced by the pancreas to regulate blood sugar), resistance to insulin, or both.

To investigate, the team measured the levels of metformin in the blood and breast milk of five women and measured the blood glucose levels in three of their infants.

Metformin concentrations in milk averaged about two-thirds the levels in blood, the researchers report. They calculate that this means that the babies received, on average, 0.65 percent of the mother’s daily dose.

Briggs and colleagues found that all three infants tested had blood glucose concentrations within the normal range, and none of the nursing infants experienced adverse effects.

“The estimated daily doses ingested by the infants seem to be clinically insignificant,” the investigators conclude. “Although additional data are required, we conclude that metformin is compatible with breast feeding.”

SOURCE: Obstetrics & Gynecology, June 2005.