Table of ContentsView AllTable of ContentsHow Metformin WorksSigns to Look ForPossible ComplicationsIf Metformin Stops WorkingFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
How Metformin Works
Signs to Look For
Possible Complications
If Metformin Stops Working
Frequently Asked Questions
Metforminis the most commonly prescribed drug used for the treatment oftype 2 diabetes.Even so, not everyone responds to metformin in the same way, and, over time, the drug can start to lose its effectiveness and stop working entirely.
When used on its own, metformin is often extremely effective in controlling blood glucose (sugar). But, for most people, this effect will gradually wane, requiring the metformin dose to be increased or another diabetes drug to be added to the treatment plan.
This article explains how metformin works and signs that the drug may no longer be working. It also outlines some of the available options should metformin fail to control your blood sugar.
AzmanL / Getty Images
Metformin (sold under the brand names Fortamet, Glumetza, and others) is an oral drug used together with healthy eating, exercise, and weight loss to manage your blood sugar.
You can take metformin on its own or in combination with other diabetes medications, includinginsulin, to help treat type 2 diabetes. People withtype 1 diabeteswho haveinsulin resistancecan also use it.
Benefits of MetforminMetformin’s effectiveness, tolerability, safety, and ability to be combined with other diabetes medications make it a first-line drug for treating people with type 2 diabetes.
Benefits of Metformin
Metformin’s effectiveness, tolerability, safety, and ability to be combined with other diabetes medications make it a first-line drug for treating people with type 2 diabetes.
Signs That Metformin Is Not Working
When taken as prescribed, metformin is highly effective at lowering blood sugar. Even so, you may experience occasional increases in blood sugar due to stress, a large meal, and other factors.
Most of the time, you don’t need to worry about these occasional increases. It is only when you notice a pattern of high blood sugar (hyperglycemia)that you should speak with your healthcare provider.
The pattern may not be due to the waning effects of the drug. It could be that you are not following dietary guidelines, have stopped exercising, or have gained excessive weight. Or, it could be that you’re not taking the drug as prescribed.
Whatever the reason, the very first indication thatmetformin is not workingis when your blood glucose levels are high. You may only realize this when yourhemoglobin A1C(a three-month average of blood sugar) is tested at your healthcare provider’s office. Or, you may start to notice when using ablood glucose monitor.
You may also start to experiencesigns and symptoms of hyperglycemia, including:
When to Call Your Healthcare ProviderSudden, unexplained increases in blood sugar that persist for several days may be a sign that your metformin is no longer working. Speak with your healthcare provider about whether your dose needs to be increased or if other diabetes medications are needed.
When to Call Your Healthcare Provider
Sudden, unexplained increases in blood sugar that persist for several days may be a sign that your metformin is no longer working. Speak with your healthcare provider about whether your dose needs to be increased or if other diabetes medications are needed.
Why Metformin Failure Is a Concern
Metformin is prescribed because your healthcare provider believes that you need it to help control your blood sugar. It is often prescribed after lifestyle interventions (like diet, exercise, and weight loss) fail to provide glucose control.
If metformin is unable to control your blood sugar, you need to take action. In people with uncontrolled or poorly controlled diabetes, excessive accumulation of glucose in the bloodstream can cause progressive damage to blood vessels, nerves, and organs.
Among the possible complications of uncontrolled diabetes are:
Does Metformin Cause Cancer?
What to Do If Metformin Isn’t Working
If metformin is not working as it should, there are different courses of action you may need to take depending on when the failure occurred.
If you just started taking metformin and don’t see an improvement in your blood sugar after several weeks, contact your healthcare provider. You may not be taking the drug correctly, or your dose could be too low.
You should also let your healthcare provider know if you are not taking metformin as prescribed because of intolerable side effects like nausea and vomiting. They may be able to switch you to an extended-release version of metformin which may lessen your side effects.
If you have been taking metformin for several years and notice that your blood sugar is suddenly starting to rise, your healthcare provider may need to add another medication to your treatment plan. There is no standardized approach as to which drug should be added, but some of the more common options include:
If metformin has stopped working, it is important to determine why and to work with your healthcare provider to get your blood sugar back under control. This can help avoiddisease complicationslike heart disease, nerve damage, or eye damage.
An Overview of Oral Diabetes Medications
Summary
Metformin is an oral diabetes medication that can help reduce blood sugar levels in people with type 2 diabetes. Although it is the most common drug used for the first-line treatment of type 2 diabetes, it doesn’t work the same for all people and can begin to lose its effectiveness over time.
Unexplained increases in blood sugar may be the first sign that metformin has stopped working. You may also experience symptoms of hyperglycemia such as excessive thirst or hunger, fatigue, and blurry vision.
Whatever the cause of the treatment failure, action needs to be taken to restore glucose control and prevent diabetes complications. This may involve improving drug adherence, correcting dosing mistakes, increasing the metformin dose, or adding another diabetes drug to the treatment plan.
A Word From Verywell
Metformin is not a “cure” for type 2 diabetes, and medication alone is not enough to keep your blood sugar in control. If you eat poorly or live an otherwise inactive lifestyle, metformin may only go so far in controlling your blood sugar.
No matter how early or advanced your diabetes is, good lifestyle choices are needed to ensure your long-term health and well-begin. This involves eating ahealthy diet, exercising regularly, taking your medications as prescribed, and losing weight if you are overweight or have obesity.
If needed, ask your healthcare provider for a referral to anutritionistor personal trainer who can help.
Frequently Asked QuestionsBecause diabetes is progressive, people may need a higher dose or additional medications the longer they have the disease. Metformin works best when combined with diet, exercise, and a healthy weight. Simply taking metformin without lifestyle changes will likely shorten the effectiveness of the drug.Common side effects of metformin include:HeartburnBloatingGasStomach painMetallic tasteDiarrheaConstipationHeadacheNausea or vomitingMetformin is taken once or twice daily with food to avoid stomach upset and other gastrointestinal side effects. Ideally, the drug is taken with the morning meal for a once-daily dose and both the morning and evening meal for a twice-daily dose.
Because diabetes is progressive, people may need a higher dose or additional medications the longer they have the disease. Metformin works best when combined with diet, exercise, and a healthy weight. Simply taking metformin without lifestyle changes will likely shorten the effectiveness of the drug.
Common side effects of metformin include:HeartburnBloatingGasStomach painMetallic tasteDiarrheaConstipationHeadacheNausea or vomiting
Common side effects of metformin include:
Metformin is taken once or twice daily with food to avoid stomach upset and other gastrointestinal side effects. Ideally, the drug is taken with the morning meal for a once-daily dose and both the morning and evening meal for a twice-daily dose.
7 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Marshall SM.60 years of metformin use: a glance at the past and a look to the future.Diabetologia.2017;60:1561-6. doi:10.1007/s00125-017-4343-yRojas LBA, Gomes MB.Metformin: an old but still the best treatment for type 2 diabetes.Diabetol Metab Syndr.2013;5:6. doi:10.1186/1758-5996-5-6MedlinePlus.Metformin.Song R.Mechanism of metformin: A tale of two sites.Diabetes Care. 2016;39(2);187-189. doi:10.2337/dci15-0013American Diabetes Association.Hyperglycemia (high blood glucose).American Diabetes Association.Complications.American Diabetes Association Professional Practice Committee.9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes-2024. Diabetes Care. 2024 Jan 1;47(Suppl 1):S158-S178. doi: 10.2337/dc24-S009
7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Marshall SM.60 years of metformin use: a glance at the past and a look to the future.Diabetologia.2017;60:1561-6. doi:10.1007/s00125-017-4343-yRojas LBA, Gomes MB.Metformin: an old but still the best treatment for type 2 diabetes.Diabetol Metab Syndr.2013;5:6. doi:10.1186/1758-5996-5-6MedlinePlus.Metformin.Song R.Mechanism of metformin: A tale of two sites.Diabetes Care. 2016;39(2);187-189. doi:10.2337/dci15-0013American Diabetes Association.Hyperglycemia (high blood glucose).American Diabetes Association.Complications.American Diabetes Association Professional Practice Committee.9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes-2024. Diabetes Care. 2024 Jan 1;47(Suppl 1):S158-S178. doi: 10.2337/dc24-S009
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Marshall SM.60 years of metformin use: a glance at the past and a look to the future.Diabetologia.2017;60:1561-6. doi:10.1007/s00125-017-4343-yRojas LBA, Gomes MB.Metformin: an old but still the best treatment for type 2 diabetes.Diabetol Metab Syndr.2013;5:6. doi:10.1186/1758-5996-5-6MedlinePlus.Metformin.Song R.Mechanism of metformin: A tale of two sites.Diabetes Care. 2016;39(2);187-189. doi:10.2337/dci15-0013American Diabetes Association.Hyperglycemia (high blood glucose).American Diabetes Association.Complications.American Diabetes Association Professional Practice Committee.9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes-2024. Diabetes Care. 2024 Jan 1;47(Suppl 1):S158-S178. doi: 10.2337/dc24-S009
Marshall SM.60 years of metformin use: a glance at the past and a look to the future.Diabetologia.2017;60:1561-6. doi:10.1007/s00125-017-4343-y
Rojas LBA, Gomes MB.Metformin: an old but still the best treatment for type 2 diabetes.Diabetol Metab Syndr.2013;5:6. doi:10.1186/1758-5996-5-6
MedlinePlus.Metformin.
Song R.Mechanism of metformin: A tale of two sites.Diabetes Care. 2016;39(2);187-189. doi:10.2337/dci15-0013
American Diabetes Association.Hyperglycemia (high blood glucose).
American Diabetes Association.Complications.
American Diabetes Association Professional Practice Committee.9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes-2024. Diabetes Care. 2024 Jan 1;47(Suppl 1):S158-S178. doi: 10.2337/dc24-S009
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
