Metformin is often one of the first medications prescribed to people with diabetes, according to the Canadian Diabetes Association (see reference 2 under Highlights of Revisions). It helps lower your blood sugar levels by decreasing the amount of glucose, or sugar, produced by your liver. It also helps your insulin, the hormone that gets the sugar out of your blood and into your cell, work better. (see reference 1 pg 1 under Clinical Pharmacology under Mechanism of Action para 1). While you do not need to avoid any foods when taking metformin, you may need to limit or avoid alcohol (see reference 1 pg 8 under alcohol intake.).
Metformin and Alcohol
If your doctor has prescribed metformin to help you get better control over your blood sugar, you should not drink an excessive amount of alcohol, including beer, wine or hard liquor (see reference 1 pg 8 under Alcohol Intake). Too much alcohol causes metformin to breakdown too much lactate, which is a by-product of glucose and amino acids, and may lead to lactic acidosis (see reference 1 pg 8 under Alcohol Intake). If you drink alcohol, it's OK to have moderate amounts while on metformin, which means up to 1 drink a day for women and 2 drinks a day for men (see reference 3 pg x). But everyone is different, so be sure to talk to your doctor first to a safe amount of alcohol for you.
When to Call Your Doctor
Lactic acidosis is actually not very common when taking metformin, but it can be dangerous, and even deadly, according to the Food and Drug Administration (see reference 1 pg 15). Symptoms that warrant an immediate call to your doctor include difficulty breathing, stomach pain, diarrhea, muscle cramps, unusual sleepiness or weakness or an all-around achiness.