FDA Revises Warnings on Metformin Use in Patients w Reduced Kidney Function

The U.S. Food and Drug Administration (FDA) is requiring labeling
changes regarding the recommendations for metformin-containing medicines
for diabetes to expand metformin’s use in certain patients with reduced
kidney function. The current labeling strongly recommends against use
of metformin in some patients whose kidneys do not work normally. We
were asked1,2 to review numerous medical studies regarding
the safety of metformin use in patients with mild to moderate impairment
in kidney function,3-14 and to change the measure of kidney
function in the metformin drug labeling that is used to determine
whether a patient can receive metformin. We have concluded our review,
and are requiring changes to the labeling of all metformin-containing
medicines to reflect this new information.

Health care professionals should follow the latest recommendations
when prescribing metformin-containing medicines to patients with
impaired kidney function. Patients should talk to their health care
professionals if they have any questions or concerns about taking

Metformin-containing medicines are available by prescription only and
are used along with diet and exercise to lower blood sugar levels in
patients with type 2 diabetes. When untreated, type 2 diabetes can lead
to serious problems, including blindness, nerve and kidney damage, and
heart disease. Metformin-containing medicines are available as
single-ingredient products and also in combination with other drugs used
to treat diabetes (see FDA Approved metformin-containing Medicines).
The current drug labeling strongly recommends against metformin use in
some patients whose kidneys do not work normally because use of
metformin in these patients can increase the risk of developing a
serious and potentially deadly condition called lactic acidosis, in
which too much lactic acid builds up in the blood.

We have concluded from the review of studies published in the medical
literature that metformin can be used safely in patients with mild
impairment in kidney function and in some patients with moderate
impairment in kidney function.3-6 We are requiring changes to
the metformin labeling to reflect this new information and provide
specific recommendations on the drug’s use in patients with mild to
moderate kidney impairment.

We are also recommending that the measure of kidney function used to
determine whether a patient can receive metformin be changed from one
based on a single laboratory parameter (blood creatinine concentration)
to one that provides a better estimate of kidney function in patients
with kidney disease (i.e., glomerular filtration rate estimating
equation (eGFR)).

Complete FDA Safety Announcement can be read here