Glucophage (metformin)
Glucophage XR (metformin hydrochloride extended release)
Fortamet (metformin hydrochloride) ?extended release
Glumetza (metformin hydrochloride) ?extended release
Riomet (metformin hydrochloride liquid)

What are Biguanides?

Metformin is the only member of the biguanides family in use today. Metformin (met-FOR-min) helps lower blood glucose by making sure your liver does not put extra glucose into the system when it is not needed. The 2013 ADA Standards of Medical Care in Diabetes recommends the inclusion of metformin (along with diet and exercise in initial diabetes treatment. A good thing about metformin is that it does not cause blood glucose to get too low (hypoglycemia) when it is the only diabetes medicine you take.

Who can take this medicine?

Adults with type 2 diabetes can take metformin with their doctor's approval and supervision. You should avoid metformin if you have liver or kidney problems, lung or heart disease, or conditions that cause low blood oxygen levels.

Who should not take this medicine?

People with certain types of heart problems such as congestive heart failure should use caution with this medicine. People with reduced kidney function or kidney disease should probably not take metformin.


Metformin when used alone is unlikely to cause low blood sugar. It is one of those medicines that always seems to help even after people have had diabetes for a while and for that reason prescribers will often just add another medicine to the metformin rather than stopping it. Metformin usually does not cause weight gain and some people will actually lose a small amount of weight when taking it.


Metformin can cause annoying stomach problems when first staring it. For that reason it is wise to start on a lower dose until your body gets used to it. If you are having surgery, tell the healthcare provider you take metformin. You should be told to stop taking metformin the day of the surgery and also get advice about when to start it back.

What dosage can I take and how should I take it?

Depending on the dosage form, whether regular tablet, long acting tablet, or liquid it is usually given from 1 to 3 times daily. The usual starting dose is 500 mg once a day. You can add another 500 mg a day, each week until you reach the final dose that your prescriber wants you to take. Many people end up at around 2000 mg per day as the final dose. It is usually taken with a meal.

What are the common side effects?

• Metformin can make you sick if you drink more than about 2 to 4 alcoholic drinks a week. If you drink more than that, tell your doctor. You should probably not take metformin.
• If you already have a kidney problem, taking metformin may make it worse. Make sure that, before you start taking metformin, your doctor knows your kidneys work well.
• If you are vomiting, have diarrhea, and can't drink enough fluids, you may need to stop taking metformin for a few days.
• Once in a while people on metformin can become weak, tired, or dizzy and have trouble breathing. If you ever have these problems, call your doctor or get medical help right away.
• You may have nausea, diarrhea, and other stomach symptoms when you first start taking metformin. These usually go away.
• You may notice a metallic taste in your mouth.

Reviewed by James A. Bennett 5/14

Last Modified Date: May 23, 2014

All content on is created and reviewed in compliance with our editorial policy.

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by Brenda Bell
As I mentioned in an earlier post, one of the benefits that made it cost-effective for me to go with the real healthcare (HSA) plan rather than the phony (HRA) plan is that my company is now covering "preventative" medicines at $0 copay. The formulary for these, as stated by CVS/Caremark (my pharmacy benefits provider), covers all test strips, lancets, and control solutions. I dutifully get my doctor to write up prescriptions for all of my testing needs, submit...
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