Metformin — what it does and why people take it

Metformin is the most commonly prescribed pill for type 2 diabetes. Doctors often start with it because it lowers blood sugar without causing much weight gain and has a long safety record. Beyond diabetes, people also use it for PCOS and sometimes to help with weight and insulin resistance.

How metformin works and who should consider it

Metformin lowers how much glucose your liver makes and helps your body use insulin better. That means fewer blood sugar spikes after meals. If you’ve been told your A1c is high or you have insulin resistance, metformin is usually one of the first options your doctor will suggest. It’s not for type 1 diabetes or as a short-term fix; it's a daily medicine that helps over time.

Practical tips: dosing, side effects, and monitoring

Start low, go slow. Most people begin on a small dose (like 500 mg once daily) and increase it over weeks. Extended-release (XR/ER) forms often cut down stomach upset. Take metformin with food to reduce nausea and diarrhea.

Common side effects are stomach cramps, gas, loose stools, or nausea—especially when you start. These usually settle in a few weeks. If GI problems persist, ask your provider about switching to the extended-release version or slower dose increases.

Serious problems are rare but worth knowing. Lactic acidosis is an uncommon but severe risk—symptoms include deep, troubling tiredness, breathing changes, or belly pain. People with very poor kidney function, severe dehydration, or heavy alcohol use face higher risk. Many clinicians won’t start or will stop metformin if eGFR is below a certain threshold; follow your doctor’s guidance.

Long-term use can lower vitamin B12 in some people. It’s smart to check B12 every year or if you notice numbness, tingling, or low energy. Regular kidney tests (creatinine/eGFR) are also standard—usually once a year or more often if you have kidney issues.

Interactions to watch for: some contrast dyes for scans and certain strong drugs can affect kidneys. If you’re having imaging with IV contrast or major surgery, your doctor may pause metformin briefly. Also tell any new prescriber you take metformin so they can check for interactions.

Pregnancy and breastfeeding: metformin is used in pregnancy for certain issues like PCOS and gestational diabetes in some cases, but decisions are personal. If you’re pregnant or planning to be, talk with your care team.

Questions to ask your prescriber: how fast to increase the dose, whether XR is better for you, how often to check labs, and what to do around scans or surgery. Keeping a simple log of side effects and blood sugars for a few weeks helps make those conversations productive.

Metformin isn’t a miracle, but it’s a reliable, well-studied tool that helps many people lower blood sugar with few downsides when used correctly. If you’re starting it or thinking about it, small dose steps, taking it with food, and routine lab checks will make it work smoother for you.