I am a nursing student from the University of North Dakota.  I
have a question regarding the use of oral antidiabetic agents while
breastfeeding.
        It is noted that blood glucose levels of breastfeeding mothers
may often be lower then they usually are.  This is because the serum
glucose is transferred to the breast, converted to lactose, and excreted
in the breast milk.  Because of this fact, some lactating mothers with
diabetes will often have a decreased need for oral hypoglycemics or
insulin (Olds, London, & Ladewig, 1996, p. 445).  However, if a
breastfeeding mother could benefit from the use of oral antidiabetics,
the risks versus the benefits would have to be carefully weighed.
        There are many factors that determine how easily a drug will pass
from maternal circulation into the breast milk.  Fat-soluble drugs easily
gain access to human milk.  In contrast, highly protein-bound medications
are restricted from leaving the maternal plasma.  Other factors include
maternal weight, pKa (helps determine the ionization of a drug at certain
plasma and milk pHs), and the difference in pH between maternal plasma
and the breast milk (Sagraves, 1997, p. 232).
        Julie Everett (1997) noted that there is still a great deal of
controversy on whether or not oral antidiabetic agents can be used on the
breastfeeding woman.  There is limited information on the extent of
distribution of these agents into the breast milk.
        The sulfonylureas are the only class of antidiabetic agents in
which there is published data about their effect on breast milk and the
infant. Tolbutamide (first-generation sulfonylurea) is considered to be
the only safe sulfonylurea while breastfeeding.  The infant should be
monitored for hypoglycemia and any other unexpected signs when using any
type of sulfonyurea.
        In theory, it is thought that acarbose (Alph-glucosidase
inhibitor) is most likely the safest of the newer agents to use in a
breastfeeding woman.  Acarbose has a large molecular size and limited
systemic absorption.  Metformin (Biguanide) is another agent that could
be adequate because it does not cause hypoglycemia.  However, this agent
could increase the risk of the infant developing lactic acidosis.  There
is not much information on the newest antidiabetic agent, troglitazone
(Thiazolidinedione).  This agent could possibly be used safely in the
breastfeeding woman (Everett, 1997, p. 319-321).

        Taking all this information into consideration, I am interested
to know what antidiabetics, if any, are commonly used in breastfeeding
women.  Additionally, when these agents are used, are there any infant
reactions that are commonly observed?  I would appreciate your thoughts
on this issue and any other comments you may have.  Thank you, Jessica
Hafey, College of Nursing (University of North Dakota).

        Everett, J. (1997). Use of Oral Antidiabetic Agents During
Breastfeeding. Journal of Human Lactation, 13(4), p. 319-321.

        Olds, S. B., London, M. L., & Ladewig, P. W. (1996). Maternal
Newborn Nursing. Addison-Wesley Nursing, A Division of The
Benjamin/Cummings Publishing Company, Inc: Menlo Park, CA.

        Sagraves, R. (1997). Pediatric Pharmacology, Drugs in Breast
Milk; a Scientific Explanation. Journal of Pediatric Health Care, 11(5),
p. 230-237.