What to Know About Metformin

Jan 25, 2022


Alto Pharmacy

While it can be overwhelming to receive a diagnosis of type 2 diabetes, following your doctor’s treatment plan can help you manage the condition and live a healthy and active life. In some cases, lifestyle changes alone can help you keep your blood sugar levels in a healthy range. For other individuals, insulin, oral medication, or a combination of both may also be necessary. Here’s what to know about metformin, one of the most common oral medications used to treat type 2 diabetes.

How metformin works

Metformin belongs to a class of medications called biguanides, which regulate your blood sugar levels by reducing how much glucose is produced during digestion. Currently, metformin is the only biguanide approved for diabetes treatment in the U.S.

Metformin is taken one to three times a day depending on your dosage and the form of metformin your doctor has prescribed. It is available in the following formulations and strengths:

  • Immediate-release tablet: 500mg, 850mg, 1000mg 

  • Extended-release tablet: 500mg, 750mg, 1000mg

  • Liquid solution: 500mg/5mL

Unlike individuals with type 1 diabetes, who are unable to produce any insulin at all and take insulin every day, individuals with type 2 diabetes typically can produce some insulin but experience problems with insulin production. They may not produce enough insulin, or cells in their body may have become resistant to insulin. Metformin does not change the amount of insulin you produce, but it does help counter insulin resistance. If your type 2 diabetes has progressed to a later stage, you may need insulin therapy to manage your blood sugar levels. Metformin is often used alongside insulin therapy at this stage to help the body use insulin more efficiently.

Metformin is also sometimes used off-label to treat polycystic ovary syndrome (PCOS), as insulin resistance may be a symptom of the condition.

Metformin side effects

Some people experience gastrointestinal issues like nausea and diarrhea as a result of taking metformin, most often when they first begin taking the medication. Taking metformin with meals often helps prevent these side effects. Your doctor may also have you start on a lower dosage of metformin and gradually work up to a larger dosage as an additional precaution against side effects.

There are fewer gastrointestinal side effects associated with the extended-release formulation of metformin. This formulation releases the medication slowly, maintaining a consistent level of the medication in your bloodstream over a longer period of time. If you have concerns about potential side effects of metformin, you may want to ask your doctor if an extended-release formulation of metformin is a good fit for your needs.


Metformin can decrease your levels of vitamin B12, which can lead to anemia — a condition defined by low levels of red blood cells — in rare cases. Your risk for anemia is greater if your diet is low in vitamin B12 and calcium. If you experience symptoms of anemia such as fatigue, dizziness, or lightheadedness, reach out to your doctor for an evaluation of your red blood cell levels.

Lactic acidosis

In rare cases, metformin may lead to lactic acidosis, an uncommon but serious condition in which an accumulation of lactic acid in the body leads to an imbalanced pH level. The chance of this side effect occurring is low, and individuals with impaired kidney function or heart failure are most at risk. To determine if metformin is a good fit for your treatment needs, your doctor will consider your overall health history and possibly order an estimated glomerular filtration rate (eGFR) test, which is a blood test that assesses your kidney function.


Hypoglycemia occurs when your blood glucose levels drop below a healthy range, most often after taking insulin. It is typically caused by not eating enough or exercising too much, and the timing of your insulin doses may also be a factor. These are some common signs of hypoglycemia to watch for:

  • Shakiness or sweating

  • Anxiety, irritability, or impatience

  • Feeling sleepy, weak, or lightheaded

  • Coordination problems, clumsiness, and confusion

  • Fast heartbeat

  • Hunger

  • Nausea

  • Blurred or impaired vision

  • Headaches

  • Seizures

When taken on its own, metformin typically does not cause hypoglycemia. However, if you take metformin with other diabetes medications including insulin, it’s important to more carefully monitor your blood sugar and be mindful of how your diet, exercise, and alcohol intake can interact with metformin.

To prevent hypoglycemia when taking metformin, be sure to take all of your diabetes medications as prescribed and on schedule, follow your doctor’s recommendations for exercise, and eat a balanced diet. In addition, make sure your doctor has a complete picture of your health history and is aware of all the medications you take.

A partner in your diabetes care

When your diabetes treatment plan includes multiple medications, staying on top of your prescriptions can be easier said than done. The Alto app can help you manage all of your diabetes needs in one place, and our dedicated diabetes support team is here to offer guidance and make sure you have everything you need for your treatment.

Reach out any time through in-app secure messaging or by phone at 1-800-874-5881 to learn how Alto can be a partner in your diabetes care.

This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition.

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