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Common Signs Metformin Is Not Working and What to Do

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  • Posted on 06th Jan, 2022 03:45 AM

Metformin is an oral medication used to treat type 2 diabetes. It may become less effective over time. Here are some signs metformin is not working. Metformin (sold under the brand names Fortamet, Glucophage, Glucophage XR, Glumetza, and Riomet) is an oral medication used in conjunction with healthy eating and exercise to manage blood sugar. It belongs to a class of medications called

Metformin (sold under the brand names Fortamet, Glucophage, Glucophage XR, Glumetza, and Riomet) is an oral medication used in conjunction with healthy eating and exercise to manage blood sugar. It belongs to a class of medications 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 (blood sugar). It also helps to increase your body’s response to insulin, the hormone made by the pancreas that helps your body use glucose for energy. Metformin increases insulin sensitivity, allowing glucose to move from your bloodstream to your cells.

Metformin can be taken in combination with most medication, including insulin and non-insulin injectable medications. When taken alone, it usually does not cause hypoglycemia. If you have a history of kidney failure, liver failure, or coronary heart failure, or drink excessively, you should talk with your healthcare provider before starting Metformin.

Type 2 diabetes is a progressive disease and medication alone is not enough to keep blood sugar in control. Over time, if metformin isn't working to keep your blood sugar at goal levels, you may need a higher dose or additional medicine.

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

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Signs Metformin Is Not Working

If your blood sugar is elevated due to a large meal or because of a stressful day, you don't need to be alarmed. However, if you notice a pattern of high blood sugars (hyperglycemia) it may mean that you need a change in your treatment plan. Elevated blood sugar levels for several days without explanation can be a sign 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, maintenance of blood sugar control with one drug (referred to as monotherapy) is often possible for only a few years. After that time, you may need additional medicine.

Your blood sugars can also be impacted by:

  • Diet
  • Exercise
  • Stress
  • Hormones
  • Illness

Perhaps you have been taking metformin for a while but haven't improved your diet or you stopped exercising. These changes can impact your blood sugar, so it's important to always work on any behavioral or lifestyle changes that can improve them.

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

How Long Does It Take for Metformin to Work?

Metformin takes some time to start working and does not lower blood sugar levels immediately—the dosage impacts the timing. When you begin taking the medication and increase the dose as prescribed, it is recommended to test fasting blood sugar levels regularly to see if your dose is working. In addition, your healthcare provider will likely recommend a hemoglobin A1C (a three-month average of blood sugar) test to assess your response.

What to Do If Metformin Isn’t Working

If metformin is a new medication and you have been taking it for a few weeks without improvement in your blood sugar levels, you should contact your healthcare provider. You may not be taking it correctly (the pill should not be crushed or cut) or perhaps your dose is not high enough. Or, if you have stomach discomfort and are taking the regular version, an extended release tablet may suit you better.

If you have been taking metformin for several years and notice that your blood sugar levels are starting to increase for no reason, it may mean that you need another medication to add to your diabetes regimen. There are many different classes of medicines that could be an appropriate addition.

As always, it will be important to eat a well-balanced diet and exercise, but ask your healthcare provider if adding another diabetes medication is necessary. This does not mean you have failed your diabetes, rather that your body needs extra help to keep your blood sugar in a healthy range.

Some diabetes medicines can assist in weight loss, which can improve glycemic control. Other medications work to reduce after-meal blood sugar levels. According to the American Diabetes Association, a patient’s specific health needs should help determine the best treatments, including:

  • Effect on other health conditions, such as those of the cardiovascular system and kidneys
  • Efficacy (how well the medicines produce the desired effect)
  • Risk for hypoglycemia (when blood sugar is too low)
  • Impact on their weight
  • Cost
  • Risk for side effects
  • Patient preferences

Voluntary Recalls

In 2020 and 2021, there were several voluntary recalls of metformin due to contamination with the potential carcinogen (cancer-causing agent) N-nitrosodimethylamine (NDMA). A late-December 2021 recall by Viona Pharmaceuticals, recalled two lots of its Metformin-Hydrocholoride Extended-Release USP 750 milligram tablets. Check with your healthcare provider to ensure you are not taking any recalled medication.


Metformin is an oral diabetes medication that when taken along with a healthy diet and exercise routine helps to reduce blood sugar levels. It can take a few weeks to reach your therapeutic dose of metformin.

Although this medication is often used as a first-line therapy for people with type 2 diabetes, there are instances in which metformin is not recommended for use. Discuss your needs with your healthcare provider and make sure you are taking the prescribed dose correctly. If you feel as though your medication is no longer working, be sure to discuss your concerns with your medical team.

A Word From Verywell 

If you have type 2 diabetes, you may have been prescribed metformin to control you blood sugars in addition to diet and exercise. Metformin is generally prescribed as a first-line treatment for diabetes and works to reduce blood sugar levels by increasing insulin sensitivity, reducing glucose absorption, and decreasing hepatic glucose output. If you are concerned that the medication is not working, it's important to discuss this with your healthcare provider.

There is no universal treatment to diabetes. Your healthcare provider's approach to care should come with you in mind. Be sure to let them know your needs, lifestyle, and budget. Do not get discouraged if metformin does not work for you as there are many other options.

Frequently Asked Questions

  • Can metformin become less effective over time?

    Because diabetes is progressive, people may need more medicine the longer they have the condition. Metformin will work best when taken along with a diabetes-friendly meal plan and in those people who are able to move their bodies and maintain a healthy weight. Simply taking medicine without lifestyle changes will likely shorten the effectiveness of the medicine.

  • What are common side effects of metformin?

    The major side effects of this medicine are upset stomach, nausea, diarrhea, vitamin B12 deficiency (with prolonged use), and, in rare cases, lactic acidosis (too much lactic acid in the bloodstream). Risk factors for lactic acidosis include renal impairment (kidney disease), use of certain drugs, being over 65 years old, undergoing radiological studies with contrast, having had surgery and other procedures, hypoxic states (low oxygen levels in your blood), excessive alcohol use, and hepatic impairment (liver disease). If you have any of these, you should not take metformin.

  • When should you take metformin?

    You should take metformin with food. Typically, it is taken once or twice a day at a low dose and increased gradually as necessary to prevent side effects. Gradually changing the concentration and taking it with food should lessen the gastrointestinal effects.

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