Metformin (
Glucophage®) is a prescription medication that is licensed to treat
type 2 diabetes (also known as noninsulin-dependent
diabetes or adult-onset diabetes). Metformin also comes in:
Generic metformin is made by numerous manufacturers. Glucophage and Glucophage XR are manufactured by Bristol-Myers Squibb.
Metformin is part of a class of
diabetes medications known as biguanide medications. The drug works in several ways. For example, it decreases the amount of sugar (glucose) made by the liver. It can also decrease the amount of sugar absorbed into the body (from the diet) and can make insulin receptors more sensitive, helping the body respond better to its own insulin. All of these effects cause a decrease in blood sugar levels.
Because the medication does not increase the amount of insulin produced by the body, it is less likely to cause dangerously low blood sugar (hypoglycemia), as many other diabetes medications can do
(see Alternatives to Metformin).
There have been several studies documenting the effects of metformin for
type 2 diabetes. In these studies, the drug has been shown to decrease fasting blood sugar and to decrease hemoglobin A1c (HbA1c). HbA1c is a test used to measure long-term blood sugar control in people with
diabetes. Normal HbA1c levels are usually less than 6 percent in people without diabetes; people with diabetes usually have higher HbA1c results.
Studies have shown that the higher the HbA1c, the greater the chance for developing long-term problems related to diabetes. This includes such problems as
heart disease,
diabetic retinopathy,
diabetic neuropathy, and diabetic nephropathy. By getting blood sugar levels under control with metformin, it may be possible to decrease the chances for developing these
diabetes complications.
When and How Do I Take It?
Some general considerations for when and how to take the medication include:
- Metformin tablets should be taken by mouth, usually one to three times daily. The long-acting form, metformin ER, should be taken once daily with your evening meal.
- The medication should be taken with food to reduce stomach upset.
- The long-acting form (metformin ER) should be swallowed whole and should not be broken or crushed.
- It should be taken at the same time(s) each day to maintain an even level of the drug in your blood.
- For the medication to work properly, it must be taken as prescribed. It will not work if you stop taking it.
The dosage that your healthcare provider recommends will vary depending on a number of factors, including:
- How well your diabetes is controlled
- Other medical conditions you may have
- Other medications you may currently be taking.
As is always the case, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
As with any medicine, there are possible side effects. However, not everyone who takes metformin will experience side effects. In fact, most people tolerate the drug well. When side effects do occur, in most cases they are minor and either require no treatment or can be easily treated by you or your healthcare provider. Serious side effects are less common.
The most common side effects include, but are not limited to:
- Diarrhea
- Nausea or vomiting
- Gas
- Weakness
- Indigestion
- Abdominal discomfort (or stomach discomfort)
- Headache.
(Click Metformin Side Effects to learn more about the specific side effects of the drug, including serious side effects to look out for. You can also read about other possible side effects by going to:
Drug Interactions With Metformin
This drug can potentially interact with a number of medicines.
What Should I Tell My Healthcare Provider?
You should talk with your healthcare provider prior to taking this medication if you have:
- Kidney problems, including kidney failure (renal failure)
- Liver problems, including liver failure or cirrhosis
- Low vitamin B12 levels (pernicious anemia)
- Congestive heart failure (CHF)
- Had a heart attack or stroke
- An upcoming surgery or procedure (including x-rays and other radiology procedures)
- Any allergies, including allergies to foods, dyes, or preservatives.
Also, let your healthcare provider know if you:
Tell your healthcare provider about all of the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.
Alternatives to Metformin
In general, type 2
diabetes treatment begins with lifestyle changes (for example, weight loss, exercise, and diet). If lifestyle changes alone are not effective at
managing diabetes, medication, such as metformin, may be necessary.
The main goal of
diabetes medicine is to lower blood sugar levels enough to reduce your risk of developing problems related to diabetes, such as heart, nerve, eye, or kidney problems. Because metformin can lower blood sugar levels, people may be able to lower their risk for developing problems related to high blood sugar.
For most people, the medication is quite effective at controlling blood sugar. It is also generally well-tolerated. However, side effects can occur -- or the medicine may not work as well as needed. In these cases, you may need to combine it with another diabetes medicine, such as
Avandia® (
rosiglitazone) or insulin. You may also wish to consider a substitute for metformin.
(Click Alternatives to Metformin to learn more about these options. To learn about controlling diabetes through lifestyle choices, click on any of the links below:
People who take too much metformin may have overdose symptoms that could include:
- Low blood sugar (hypoglycemia) (see Metformin and Blood Sugar)
- Lactic acidosis (see Metformin and Lactic Acidosis)
- Fainting
- Shakiness
- Fast heartbeat (tachycardia)
- Confusion
- Sweating
- Muscle pain
- Trouble breathing
- Abdominal pain (stomach pain)
- Feeling cold
- Dizziness
- Slow or irregular heartbeat.
If you happen to overdose, seek medical attention immediately.
The medication should be stored at room temperature, away from moisture or heat. The tablets should be kept in an airtight container.
Keep metformin and all medications out of the reach of children.
What Should I Do If I Miss a Dose?
If you do not take your metformin as scheduled, take your next dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose.
Metformin tablets are available in five strengths:
- Metformin 500 mg tablets
- Metformin 625 mg tablets
- Metformin 750 mg tablets
- Metformin 850 mg tablets
- Metformin 1000 mg tablets.
- Metformin ER 500 mg tablets.
- Metformin ER 750 mg tablets.
Long-acting metformin 1000 mg tablets are also available and are sold under the brand names of
Fortamet and
Glumetza. A liquid version of metformin, called
Riomet, is also available.
Both brand-name and generic metformin and metformin ER are currently licensed for sale. However, generic versions of Fortamet, Glumetza, and Riomet are not licensed for sale at this time.
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