What to Know About Metformin
By Amy Campbell, MS, RD, LDN, CDE
W
hile there are a growing num-
ber of classes of drugs to help
treat Type 2 diabetes, most clinical
guidelines suggest that metformin be
prescribed first, as it’s safe, effective
and inexpensive. In addition, metfor-
min may provide other health ben-
efits besides helping to lower blood
sugar. Not everyone understands how it
works, and there are many unfounded
claims that this drug is dangerous.
There are risks to taking any drug, and
while metformin isn’t for everyone,
there’s a lot about this drug that’s help-
ful and important to know.
Metformin has been around
for a long time.
Metformin contains a substance called
guanidine, which can lower blood sug-
ars. Guanidine is found in an herb
called goat’s rue (also known as French
lilac), and this herb has been used to
treat diabetes since the early 1900s.
The Food and Drug Administration
approved metformin in 1995, although
it’s been used in the UK since 1958.
Metformin can treat
prediabetes.
About 84 million people in the U.S. have
prediabetes; without intervention, about
70 percent of them will go on to develop
Type 2 diabetes. The Diabetes Preven-
tion Program (DPP), a landmark clini-
cal trial, showed that lifestyle changes
(weight loss, healthy eating, physical
activity) can lower the risk of getting
Type 2 diabetes by close to 60 percent.
It also showed that taking metformin
can lower the risk by 31 percent. Data
from the ongoing DPP study indicates
that lifestyle changes or metformin
could reduce or delay the onset of Type
2 diabetes by up to 15 years.There are different ways to
take metformin.
Metformin comes in tablet form that is
typically taken once or twice a day. It’s
also available as an extended-release
tablet that is taken once a day. A liquid
form of metformin, called Riomet®, is
an option if swallowing pills isn’t for
you. Metformin is available as a generic
drug (making this very affordable), but
the brand-name versions include Glu-
cophage®, Glucophage XR, Glumetza,
Fortamet and Riomet. In addition,
metformin is available in combination
with other types of diabetes medicines.Metformin is linked to
vitamin B12 deficiency.
Vitamin B12 is needed for optimal
brain and nervous system function.
Taking metformin for an extended
period of time raises the risk of devel-
oping a B12 deficiency. Metformin
appears to limit the absorption of B12
in the stomach and from the blood-
stream into cells. A B12 deficiency can
lead to megaloblastic anemia, neu-
ropathy, memory loss and fatigue. If
you take metformin, check with your
doctor about getting your B12 levelchecked and whether you may need
to supplement with B12.Metformin is used to
treat PCOS.
PCOS (polycystic ovary syndrome) is a
hormonal disorder that affects women
of childbearing age. Symptoms include
irregular menstrual periods, an excess
of androgen (a male hormone) and
numerous cysts on the ovaries. PCOS
is also associated with obesity, hirsutism
(excessive body hair growth), difficulty
becoming pregnant and insulin resis-
tance. Hormones may be prescribed
to help regulate the menstrual cycle
and encourage ovulation. Lifestyle
changes, such as losing weight and
being physically active, can help. In
addition, metformin may be prescribed
to improve insulin resistance, which
not only decreases the risk of Type
2 diabetes but also helps to balance
hormone levels, helping to regulate
menstruation and ovulation.You may need to stop taking
metformin before having a
test that uses contrast dye.
If you take metformin and are due
to have a computerized tomography
(CT) scan, magnetic resonance imag-
ing (MRI) or angiogram that involves
the use of intravenous therapy (IV)
contrast dye, talk with your doctor
about stopping your metformin before
the procedure. The contrast dye may
cause minor, short-term changes to Shutterstock/Tatiana^ Bura
vleva20 May/June 2019