||Glucophage, Glucophage XR
How It Works
Metformin decreases the level of
androgens produced by the ovaries and adrenal glands.
It also helps the body use
insulin and may reduce the risk of
Metformin lowers blood sugar
- Decreasing the amount of sugar produced by the
- Increasing the amount of sugar absorbed by muscle cells and
decreasing the body's resistance to insulin (insulin resistance).
When blood sugar is lower, less insulin is needed, so the
body makes less insulin. And when insulin is lower, the body produces a lower
level of androgens.
Why It Is Used
Metformin is a diabetes medicine
sometimes used for lowering insulin and blood sugar levels in women with
polycystic ovary syndrome (PCOS). This helps regulate
menstrual cycles, start ovulation, and lower the risk of miscarriage in women
with PCOS. Long-term use also lowers diabetes and heart disease risk related to
high insulin levels.2
Metformin can be used to treat women who have PCOS to reduce
insulin levels and promote normal ovarian function. Metformin is best used in
addition to eating a healthy diet, losing weight, and exercising
How Well It Works
Metformin lowers insulin, androgen,
cholesterol levels. It also improves metabolism in
women who are insulin-resistant.
- Metformin may be useful in restoring regular menstrual cycles and
starting ovulation in about 45% of women with PCOS.3
- Clomiphene (Clomid) and metformin may be more effective when they
are taken together. But more research is needed to confirm if this is
- Some studies show that taking metformin has helped with
in vitro fertilization (IVF). But other research did
not support this.
- Metformin may lower the risk of
gestational diabetes in women with PCOS, but this has
not yet been confirmed by research. Metformin is probably safe to take while
you are pregnant. But because metformin is only FDA-approved for the treatment of
diabetes, you should talk with your doctor about the use of this medicine for
reducing your risk for miscarriage or treating PCOS symptoms.
The most common side effects of metformin
- Loss of
- Increased abdominal
- A metallic taste.
These side effects occur 20% to 30% of the time. Side
effects usually decrease over time. The dosage of metformin is usually
increased gradually to prevent these possible side effects.4
Blood levels of vitamin B12 can decrease in
women who take this medicine, but the lower level usually does not cause health
problems. Doctors do recommend that women on metformin take a daily multiple
A rare side effect of taking metformin is a
condition called lactic acidosis. This happens when metformin builds up in the
blood instead of being removed by the kidneys. If not treated, this acid
buildup can lead to coma and death.
Metformin should not be used
by women who:
- Are dehydrated from not eating or drinking, or from having a
- Are about to have a surgical procedure or an X-ray with
- Have kidney or liver problems.
excessive amounts of alcohol.
The use of metformin during pregnancy is not well
researched. So if you are pregnant or are trying to get pregnant, be sure to
talk with your doctor about what is best for you.
Reference for a full list of side effects. (Drug Reference is not available in
What To Think About
You may need to stop taking
metformin temporarily before major surgery or other medical procedures, such as
X-rays that use contrast dyes. Talk to your doctor
about this before your surgery or procedure.
The effect of
metformin may be increased if you also take cimetidine (Tagamet). Before taking
metformin, talk with your doctor about any other medicines you are
Metformin is safe to use in teenage girls who have PCOS. Some
experts suggest starting long-term metformin therapy when PCOS is first
diagnosed, with the goal of lowering the risks of diabetes, infertility, and
heart disease. But the safety of long-term treatment is not yet known.1
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Speroff L, Fritz MA (2005). Anovulation and the
polycystic ovary. Clinical Gynecologic Endocrinology and Infertility, 7th ed., pp. 465-498. Lippincott Williams and
Ehrmann DA (2005). Polycystic ovary syndrome.
New England Journal of Medicine, 352(12):
Lord JM, et al. (2003). Metformin in polycystic ovary
syndrome: Systematic review and meta-analysis. BMJ,
Barbieri RL (2007). Polycystic ovary syndrome. In DC
Dale, DD Federman, eds., ACP Medicine, section 16, chap.
5. New York: WebMD.