- It tells your liver to make less glucose.
- It lowers your insulin resistance, which means it makes your muscles use insulin better so glucose can get into them instead of staying in your blood.
- It helps your intestines absorb less glucose from your food.
It's usually the first medicine doctors prescribe for type 2 diabetes. Some brand names are:
All of those are pills except Riomet, which is a liquid.
Some "combination" pills have metformin with another medicine, including:
- Glipizide and metformin (Metaglip)
- Glyburide and metformin (Glucovance)
- Pioglitazone and metformin (Actoplus Met)
- Repaglinide and metformin (Prandimet)
- Saxagliptin and metformin (Kombiglyze)
- Sitagliptin and metformin (Janumet)
If you're taking a combination pill, or metformin with other diabetes medications or insulin, check with your doctor about how likely you are to have low blood sugars. If you're taking metformin by itself, you probably won't have low blood sugars.
You might see the shell part of an extended-release pill in your poop. If you do, don't worry. The medication has gone into your body, and you shouldn't take any extra pills.
Metformin can cause problems in your gut, but they usually go away in a few weeks. You could have:
They could come back if your doctor raises your dose. Taking metformin with food can help.
When you use metformin for a long time, it could lower the amount of vitamin B-12 in your body too much. Your doctor may want to check your B-12 level, especially if you have anemia or nerve damage in your feet or hands (peripheral neuropathy).
One large study has linked long-term metformin use to higher chances of getting Alzheimer's dementia and Parkinson's disease. But we need more research to understand the connection better and what it means.
Some people who take metformin can get a lactic acid buildup in their blood. It's rare and more likely to happen if you:
- Have kidney or liver disease
- Drink a lot of alcohol
- Have severe congestive heart failure
- Are sick with fever, diarrhea, or throwing up
- Are dehydrated
It's serious, so call your doctor right away when you:
- Have trouble breathing
- Feel weak or your muscles ache
- Have stomach pain or cramps
- Feel cold
- Notice changes in your heartbeat
- Get dizzy or faint
Before Surgery, X-rays, or Scans
If you're going to have surgery, or any kind of X-ray or scan that uses dye injected into your body, let your health team know that you take metformin. You may have to stop taking it for a few days so the procedure goes well, but you'll need to talk to your doctor first about how to control your blood sugar.