In May 2020, the Food and Drug Administration (FDA) recommended that some makers of metformin extended release remove some of their tablets from the U.S. market. This is because an unacceptable level of a probable carcinogen (cancer-causing agent) was found in some extended-release metformin tablets. If you currently take this drug, call your healthcare provider. They will advise whether you should continue to take your medication or if you need a new prescription.

If a person with type 2 diabetes experiences side effects of metformin, they may wish to contact a healthcare professional about alternative options to help them manage their condition.

Type 2 diabetes mellitus (T2DM) occurs when the body’s cells stop responding to insulin appropriately. As a result, levels of glucose, or sugar, in the blood rise too high.

Certain lifestyle factors can increase the risk of T2DM, including:

  • being overweight or obese
  • engaging in low levels of physical activity
  • eating a poor diet

Metformin is an oral medication that healthcare professionals often prescribe to help treat T2DM. Metformin can help to control the amount of sugar in the blood. In people with prediabetes, the drug can also help prevent or delay the onset of the condition. However, metformin may not be suitable for everyone and can cause side effects, such as digestive problems.

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Metformin is an effective treatment for T2DM. It is often the first-line drug therapy for treating T2DM. It helps lower blood glucose levels by:

  • making the body’s cells more sensitive to insulin
  • slowing the release of glucose stored in the liver
  • slowing the absorption of glucose from food in the gut

However, metformin has a number of potential side effects. Some are common, while others are rare.

Common side effects of metformin can include:

A person should talk to a doctor before stopping metformin treatment. Taking the medication with food can help reduce the risk of digestive problems.

Less common side effects

In some people, metformin causes blood glucose levels to drop too low. The medical term for this is hypoglycemia. Hypoglycemia is more likely to occur if a person is taking other diabetes medications, such as insulin, as well as metformin.

There is also a very low risk of developing a condition called lactic acidosis. This is when lactic acid builds up in the blood. When it occurs due to metformin, it is known as metformin-associated lactic acidosis (MALA). Lactic acidosis can be life-threatening.

Certain people taking metformin may also have a risk of kidney damage. A 2018 study suggests that metformin may reduce kidney function in people with both moderate chronic kidney disease and T2DM.

Due to the potential side effects of metformin and other antidiabetic medications, a person may prefer to manage T2DM through lifestyle changes if possible. Additionally, those who experience no side effects may also wish to avoid the long-term use of medication.

Many people with T2DM find that they can manage their condition through lifestyle changes alone. These can include:

  • Making dietary changes: A 2017 review found that changing the diet may significantly reduce T2DM symptoms and prevent complications.
  • Losing weight: In a 2018 study, almost half of the participants reversed their T2DM and came off antidiabetic medications following a 12-month weight loss program.
  • Exercising regularly: Evidence notes that various types of physical activities can not only enhance health, but also help manage sugar levels due the glucose-lowering effects of exercise.

Stopping smoking and reducing or avoiding alcohol can also help control symptoms.

When a person chooses to stop taking metformin, or any other antidiabetic medication, there is a risk of symptoms becoming worse.

It is, therefore, essential that people manage their symptoms through sustainable lifestyle changes involving the diet, weight management, and regular exercise.

If left untreated, high blood glucose levels can lead to complications, such as:

Read on to learn more about the potential complications of T2DM.

A person should consult their doctor before stopping metformin or any other antidiabetic medication.

A person can stop using this drug safely if they are able to effectively manage their T2DM through sustainable lifestyle changes. These should involve:

  • dietary choices
  • weight management
  • regular exercise

A doctor will often use certain criteria to determine whether it is safe for an individual to stop taking metformin. These criteria may include:

  • having a fasting or pre-meal blood glucose level of 80–130 milligrams per deciliter (mg/dL)
  • having a random or after-meal blood glucose level of under 180 mg/dL
  • having a hemoglobin A1c result of under 7%

A doctor can give advice about choosing the right diet and exercise plans. They can also help set realistic goals and provide monitoring and support. If necessary, they can also refer a person to a dietician or another specialist.

Read on to learn more about diabetes care teams.

People who do not wish to continue using metformin can consult their doctor about alternative options. These may include:

Dipeptidyl peptidase 4 (DPP-4) inhibitors

These medications may help to improve A1C scores without causing hypoglycemia. They work by preventing the breakdown of glucagon-like peptide 1 (GLP-1) and gastric inhibitory peptide (GIP) by an enzyme known as DPP-4.

GLP-1 and GIP are natural hormones that help to reduce blood glucose levels in the body. As such, using DPP-4 inhibitors allows these hormones to remain active for longer. Typically, DPP-4 inhibitors are well tolerated.

Examples include Tradjenta and Januvia.

GLP-1 and dual GLP-1/GIP receptor agonists

Both GLP-1 and GIP are natural hormones that can help to regulate glucose levels. These medications have a similar effect to the natural hormones, but are resistant to being broken down by DPP-4. These drugs can help to lower blood glucose and may also aid weight loss and help prevent heart disease.

Examples of GLP-1 receptor agonists include Trulicity, Byetta, and Ozempic. Currently, the only dual GLP-1/GIP receptor agonist available is Mounjaro.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors

Glucose in the blood passes through the kidneys, where the body either excretes it in urine or reabsorbs it back into the blood. SGLT2 helps to reabsorb glucose in the kidneys. As such, SGLT2 inhibitors block this action, helping the body to eliminate excess glucose in the urine.

These drugs may help to improve blood glucose levels, aid weight loss, and decrease blood pressure. A doctor may prescribe them for individuals with T2DM who also have heart or kidney problems. However, they may increase the risk of genital yeast infections.

Examples include Invokana, Jardiance, and Farxiga.


These drugs help to stimulate the beta cells in the pancreas to release more insulin. All sulfonylurea drugs have similar effects on blood sugar levels, but differ in side effects, drug interactions, and how often people take them. Common side effects may include hypoglycemia and weight loss.

Examples include Amaryl and Glucotrol XL.

Thiazolidinediones (TZDs)

These drugs help insulin to work better in muscle and fat and also reduces glucose production in the liver. TZDs can help lower blood sugar without a high risk of hypoglycemia. However, drugs in this class can increase the risk of heart failure in some people, and may also cause fluid retention in the legs and feet.

Examples include Avandia and Actos.

Read on to learn more about diabetes medication and drugs for T2DM.

Some FAQs about metformin may include:

What is the major side effect of metformin?

The most common side effects of metformin are stomach problems, such as diarrhea, nausea, vomiting, and gas.

Why do doctors no longer recommend metformin?

Doctors still often prescribe metformin to help treat T2DM. However, metformin may not be suitable for everyone with T2DM. For example, a doctor may prescribe alternative treatments, such as SGLT2 inhibitors, in people with kidney problems.

What organ is metformin hard on?

Metformin does not harm the kidneys. However, if a person has kidney problems, they are more likely to experience complications from metformin, such as lactic acidosis.

What should people avoid when taking metformin?

When taking metformin, it is advisable to avoid or reduce certain foods, such as processed foods and those high in saturated fats, trans fats, sodium, and sugar. It is also advisable to avoid certain medications, such as diuretics and medication to treat heart problems and hypertension.

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