If the doctors are not happy with breastfeeding in the presence of metformin ,
how about asking if they would use another drug instead?

The MP ratio does not seem to have been determined in humans. The low
bioavailability would make it relatively safe normally. If the baby is
monitored for hypoglycaemia surely the value of breastmilk outweighs the small
chance of side effects. I would suggest the mother points out the link between
not bf and insulin dependant diabetes and that she is keen to bf.

Wendy Jones
Breastfeeding Network Uk
Pharmacist