Metformin

What it is

Metformin belongs to a class of drugs called biguanides. It comes as a tablet, a long-acting tablet, and a liquid taken by mouth.

Source: MedlinePlus (NIH): Metformin: MedlinePlus Drug Information ↗

How it's thought to work

Metformin lowers the sugar absorbed from food and the sugar made by the liver. It also makes the body respond better to insulin, a natural substance that controls blood sugar.

Source: MedlinePlus (NIH): Metformin: MedlinePlus Drug Information ↗

What people use it for

• It is often the first diabetes pill that health care providers prescribe for type 2 diabetes.
• Metformin is not used to treat type 1 diabetes.
• It may be combined with another medicine if blood sugar is not in range after 3 months.
• It controls diabetes but does not cure it.
• Metformin may help improve cholesterol levels and help people with diabetes lose some weight.

Sources: MedlinePlus (NIH): Type 2 diabetes - oral medicines: MedlinePlus Medical Encyclopedia ↗ · MedlinePlus (NIH): Metformin: MedlinePlus Drug Information ↗

What the research has found so far

Studied for aging mostly through observational data. A large aging trial has been proposed.

On Metformin and aging, PubMed lists 32 trials in people, 71 studies that watched people over time, 277 animal and lab studies. See the counts and searches

Side effects and risks

• Listed side effects include diarrhea, nausea, stomach discomfort, gas, indigestion, and constipation.
• Other listed side effects include weakness, taste change, headache, skin flushing, nail changes, muscle pain, and rash.
• The most common side effect is diarrhea.
• People taking metformin sometimes become low in vitamin B12.
• It has a low risk of low blood sugar.
• Metformin may cause changes in blood sugar.
• People on the extended-release tablets may see an empty tablet shell in their stool, which does not mean the dose was missed.

Sources: MedlinePlus (NIH): Metformin: MedlinePlus Drug Information ↗ · MedlinePlus (NIH): Type 2 diabetes - oral medicines: MedlinePlus Medical Encyclopedia ↗

Who should be careful, and drug interactions

• The page says to tell a doctor about kidney disease, and that the doctor will probably say not to take metformin.
• Before surgery or dye x-ray procedures, metformin may need to be stopped and restarted after at least 48 hours.
• Drinking alcohol raises the risk of lactic acidosis or may lower blood sugar.
• People with liver or kidney disease or heavy drinkers should not take metformin, according to this page.

Sources: MedlinePlus (NIH): Metformin: MedlinePlus Drug Information ↗ · MedlinePlus (NIH): Type 2 diabetes - oral medicines: MedlinePlus Medical Encyclopedia ↗

Approval and legal status

• FDA: DailyMed - METFORMIN HYDROCHLORIDE- metformin hydrochloride tablet ↗

Amounts used in studies

What studies or labels describe, not a recommendation.

• The label-style information lists the regular tablet as usually taken with meals two or three times a day.
• The extended-release tablet is usually taken once daily with the evening meal.
• The liquid is usually taken with meals one or two times a day.
• Doctors may start with a low dose and raise it no more often than every 1–2 weeks.

Source: MedlinePlus (NIH): Metformin: MedlinePlus Drug Information ↗

Roughly what it costs

We don't have prices for this yet.

Questions to ask your doctor

• Is Metformin a sensible option for me, given my health and the medicines I take?
• Could Metformin interact with any medicine or supplement I already take?
• What side effects should I watch for, and when should I stop or call you?
• Would Metformin be used for its approved purpose, or off-label for aging?
• How would we tell whether it is helping, and when should we review it?