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What is Metformin?

Generic metformin tablets
Generic metformin tablets, sold in the United Kingdom.
Credit: Public domain.

Metformin is a prescription drug used primarily in the treatment of type II diabetes. It is intended to help control the amount of sugar in the blood, and can be used on its own or combined with other medications. In the United States, it is sold under the brand names Fortamet, Glucophage, Glumetza and Riomet.

Metformin aims to decrease glucose production in the liver, consequently lowering the levels of glucose in the bloodstream. Metformin also designed to decrease the amount of glucose one absorbs from food, and increase the body’s response to insulin, which naturally controls glucose-levels in blood. While Metformin is used to treat type II diabetes, a condition in which the body does not use insulin in a normal and effective way, it is not used to treat type I diabetes, a condition in which the body does not produce insulin at all.

Metformin & PCOS

Metformin is sometimes prescribed to treat polycystic ovarian syndrome (PCOS). However, this use is not yet approved by the Federal Drug Administration (FDA), and the National Institutes of Health (NIH) recommends talking to a doctor about the drug’s potential in this category.

According to the University of Chicago Medical Center, lowering insulin levels also lowers the amount of testosterone produced, thus theoretically decreasing the symptoms of PCOS that are associated with excess testosterone. Metformin may help restore regular menstrual cycles and improve metabolism, thus possibly leading to weight loss in women with PCOS. It may also help reduce the chance of miscarriage or gestational diabetes and improve the chance of successful in-vitro fertilization (IVF), though according to the NIH, research is inconclusive on all of these topics.

Dosage

Metformin can be taken as a tablet, an extended-release oral tablet or a liquid. Extended-release tablets should be swallowed, not chewed, crushed or split. The regular tablet is taken with meals two or three times a day, the extended-release tablet is taken once a day with a meal in the evening, and the liquid is usually taken with meals once or twice a day.

Doctors often start patients on low doses of metformin and gradually increase the dosage. Patients must carefully monitor blood sugar while taking metformin so that doctors will be able to determine how well the drug is working. The NIH stresses that patients should not stop taking metformin without consulting a doctor, even if they feel well. Metformin cannot cure diabetes, only help control it.

In the case of a missed dose, the patient should take the missed dose as soon as he or she remembers it, unless it is almost time for the next dose. In that case, the patient should skip the missed dose and continue on the regular dosing schedule. The NIH says that patients should not take a double dose to make up for a skipped one.

It is important for diabetic patients to follow a healthy eating and exercise routine as outlined by their doctor. In the case of eating or exercising more or less than usual, a doctor should be informed. Such change can affect blood sugar levels, and doctors will provide specific instructions should this happen.

Drinking alcohol can potentially lower blood sugar levels, so it is important for patients to talk to a doctor about how much alcohol, if any, is safe to drink while taking metformin.

Side effects

According to the NIH, common side effects of metformin include:

  • diarrhea
  • bloating
  • stomach pain
  • gas
  • indigestion
  • constipation
  • unpleasant metallic taste
  • heartburn
  • headache
  • skin flushing
  • changes in finger or toenails
  • muscle pain

If any of these side effects persist, become severe, disappear and then return, or only appear after taking metformin for a long time, a doctor should be consulted.

More serious side effects are chest painand rash.If these side effects occur, patients should immediately consult a doctor or seek emergency treatment. Patients should talk to their doctor about other risks of metformin.

Risks

The NIH notes that metformin may rarely cause lactic acidosis, a serious, life-threatening condition. People over 80 years old who have had a heart attack, stroke, diabetic ketoacidosis, coma, or heart, kidney or liver disease should talk to their doctors about this risk of taking metformin.

Drinking alcohol can also increase the risk of lactic acidosis.

The research is inconclusive on whether or not metformin is safe to take during pregnancy. For example, the Mayo Clinic suggests that it is safe, while a 2008 study in the U.S. National Library of Medicine says, “is currently recommended that metformin be discontinued with the first positive pregnancy test result.” Before getting a prescription, women should tell their doctors if they are pregnant, breast-feeding, or planning to become pregnant. If they get pregnant while taking metformin, a doctor should be informed immediately.

Abuse and overdose

Though not categorized as a controlled substance, it is possible to overdose on metformin. According to the NIH, symptoms of overdose include:

  • hypoglycemia and its symptoms
  • extreme tiredness
  • weakness
  • discomfort
  • vomiting
  • nausea
  • stomach pain
  • decreased appetite
  • deep, rapid breathing
  • shortness of breath
  • dizziness
  • lightheadedness
  • abnormally fast or slow heartbeat
  • flushing of the skin
  • muscle pain
  • feeling cold

In the case of overdose, patients should contact their local poison control center. If the patient isn’t breathing or has collapsed, call 911.

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