Common Signs Metformin Not Working and What to Do

Metformin (sold under the brand names Fortamet, Glucophage, Glucophage XR, Glumetza, and Riomet) is an oral medication used in conjunction with a healthy diet and exercise to control blood sugar.It belongs to a class of drugs called Biguanides.

Metformin is the most widely used first-line type 2 diabetes drug. Its main function is to stop the liver from releasing too much glucose (sugar) into the bloodstream. It also helps increase your body’s response to insulin, a hormone produced by the pancreas that helps your body use glucose for energy. Metformin increases insulin sensitivity, which moves glucose from your blood to your cells.

Metformin can be taken with most medicines, including insulin and non-insulin injectable medicines. When taken alone, it usually does not cause low blood sugar. If you have a history of kidney failure, liver failure, or coronary heart failure, or if you drink too much alcohol, you should consult your healthcare provider before starting metformin.

Type 2 diabetes is a progressive disease in which medication alone is not sufficient to control blood sugar. Over time, if metformin does not keep your blood sugar at target levels, you may need a higher dose or additional medication.

In this article, you’ll learn more about metformin and the signs that it might not be working.

Signs Metformin is not working

If your blood sugar spikes due to a large meal or the stress of the day, you don’t need to panic. However, if you notice a pattern of hyperglycemia (hyperglycemia), it may mean that you need to change your treatment plan.

Unexplained increases in blood sugar levels for several days may indicate that your metformin is no longer working or that your dose needs to be changed.

Type 2 diabetes is a progressive disease, and in some people, blood sugar control is usually maintained for only a few years with a single drug (called monotherapy). After that, you may need additional medication.

Your blood sugar may also be affected by:

  • diet
  • exercise
  • pressure
  • hormones
  • disease

Maybe you’ve been taking metformin for a while and your diet hasn’t improved, or you’ve stopped exercising. These changes can affect your blood sugar, so it’s important to always commit to any behavior or lifestyle changes that can improve them.

If it’s unclear why your blood sugar is elevated, work with your healthcare provider and meet with a certified diabetes care and education specialist who can help you with your specific needs.

How long does it take for metformin to work?

Metformin takes some time to start working and doesn’t lower blood sugar levels right away — the dose affects the timing.

When you start the medication and increase your dose as prescribed, it is recommended to test your fasting blood sugar levels regularly to see if your dose is working.

Additionally, your healthcare provider may recommend a hemoglobin A1C (three-month average blood sugar) test to evaluate your response.

What to do if metformin doesn’t work

If metformin is a new drug and you have been taking it for several weeks and your blood sugar levels have not improved, you should contact your healthcare provider. You may not be taking it correctly (the pill should not be crushed or cut), or your dose may be too low.

Less commonly, you may not have type 2 diabetes, but another type of diabetes—such as type 1 diabetes or latent autoimmune diabetes in adults (LADA)—and need insulin to lower blood sugar levels.

Side effects such as nausea and diarrhea are also common for people starting metformin for the first time. This does not necessarily mean that the drug is not working. If you have an upset stomach and are taking the regular version, extended-release tablets may be better for you.

If you’ve been taking metformin for several years and notice that your blood sugar levels start to rise for no apparent reason, it may mean that you need another drug to add to your diabetes regimen. There are many different classes of medications that can be appropriate supplements.

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As always, eating a balanced diet and exercising is important, but ask your healthcare provider if you need to add another diabetes medication. This doesn’t mean your diabetes is failing, but your body needs extra help to keep your blood sugar in a healthy range.

Some diabetes medications can help with weight loss, which can improve blood sugar control. Other medications can lower blood sugar levels after meals. According to the American Diabetes Association, a patient’s specific health needs should help determine the best treatment, including:

  • Effects on other health conditions, such as the health of the cardiovascular system and kidneys
  • Efficacy (the extent to which the drug produces the desired effect)
  • Risk of hypoglycemia (when blood sugar is too low)
  • effect on their weight
  • cost
  • risk of side effects
  • patient preference

Voluntary recall

In 2020 and 2021, there have been several voluntary recalls of metformin due to contamination with the potential carcinogen (carcinogen) N-nitrosodimethylamine (NDMA). Viona Pharmaceuticals recalled two lots of metformin hydrochloride extended-release USP 750 mg tablets in late December 2021. Check with your healthcare provider to make sure you are not taking any of the recalled drugs.


Metformin is an oral diabetes medication that helps lower blood sugar levels when taken with a healthy diet and daily exercise. It may take several weeks to reach the therapeutic dose of metformin.

Although this drug is often used as first-line treatment for people with type 2 diabetes, metformin is not recommended in some cases. Discuss your needs with your healthcare provider and make sure you are taking the prescribed dose correctly. If you feel that your medication is no longer working, be sure to discuss your concerns with your healthcare team.

VigorTip words

If you have type 2 diabetes, you may already be taking metformin to control your blood sugar in addition to diet and exercise. Metformin is often prescribed as a first-line treatment for type 2 diabetes, lowering blood glucose levels by increasing insulin sensitivity, reducing glucose absorption, and reducing hepatic glucose output. If you are concerned that your medication is not working, it is important to discuss this with your healthcare provider.

There is no universal cure for diabetes. You should keep in mind your healthcare provider’s approach to care. Be sure to let them know your needs, lifestyle and budget. Don’t be discouraged if metformin doesn’t work for you, as there are many other options.

Frequently Asked Questions

  • Will metformin become less effective over time?

    Because diabetes is progressive, the longer people have the disease, the more medication they may need. Metformin works best when taken with a diabetes-friendly meal plan and with people who are able to move their bodies and maintain a healthy weight. Simply taking the drug without changing your lifestyle may shorten the drug’s effectiveness.

  • What are the common side effects of metformin?

    The main side effects of this medicine are upset stomach, nausea, diarrhea, vitamin B12 deficiency (with long-term use), and, in rare cases, lactic acidosis (too much lactic acid in the blood). Risk factors for lactic acidosis include impaired kidney function (kidney disease), use of certain medications, age over 65, studies with contrast media, surgery and other procedures, hypoxia (low levels of oxygen in the blood) ), excessive alcohol use, and liver damage (liver disease). If you have these, you should not take metformin.

  • When should I take metformin?

    You should take metformin with meals. Usually, it is taken in low doses once or twice a day and gradually increased as needed to prevent side effects. Gradual changes in concentration and administration with food should reduce gastrointestinal effects.