Metformin is generally a safe and effective treatment for type 2 diabetes. However, it can cause side effects, and some people may prefer to manage the condition through lifestyle and dietary changes.

Type 2 diabetes 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 type 2 diabetes, including:

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

Metformin is an oral medication that helps control the effects of type 2 diabetes. In people with prediabetes, the drug can also help prevent or delay the onset of the condition. Doctors prescribe metformin to nearly 120 million people worldwide.

In this article, we look at the side effects of metformin and explore the reasons that a person with type 2 diabetes might want to stop taking it. We also describe the risks of stopping the medication and how to do it safely.

Side effects of taking metformin

Metformin is an effective treatment for type 2 diabetes. 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 include:

• digestive problems, such as diarrhea, vomiting, and flatulence
• a vitamin B12 deficiency
• slight weight loss

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

Around 30% of people taking metformin in the long-term experience vitamin B12 deficiency. Symptoms can include:

• weakness
• shortness of breath
• nerve damage

Less common side effects

In some people, metformin causes blood glucose levels to drop too low, and the medical term for this is hypoglycemia.

Hypoglycemia is more likely to occur if a person is taking insulin as well as metformin.

There is also a very low risk of developing a condition called lactic acidosis, which results from a buildup of lactic acid. This condition 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 chronic kidney disease and type 2 diabetes.

Other considerations

Exercise can reduce insulin resistance and improve type 2 diabetes symptoms. However, some research suggests that taking metformin in the short-term may reduce the positive effects of exercise on insulin sensitivity.

Reasons for stopping metformin

Due to the side effects of metformin and other antidiabetic medications, a person may prefer to manage type 2 diabetes through lifestyle changes. Even people who experience no side effects may wish to avoid the long-term use of medication.

Many people with type 2 diabetes 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 type 2 diabetes symptoms and prevent complications.
• Losing weight: In a 2018 study, almost half of the participants reversed their type 2 diabetes and came off antidiabetic medications following a 12-month weight loss program.
• Exercising regularly: A 2014 study suggests that a single exercise session can help to temporarily improve symptoms of type 2 diabetes.

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

Risks of stopping metformin

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:

• impaired vision, or diabetic retinopathy
• kidney problems, or diabetic nephropathy
• nerve damage, or diabetic neuropathy
• heart problems
• sexual health issues
• foot problems

Stopping metformin safely

Speak to a doctor before stopping metformin or any other antidiabetic medication.

A person can go off the drug safely if they are able to effectively manage their type 2 diabetes with sustainable lifestyle changes. These should involve:

• diet
• 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 include:

• having a fasting or pre-meal blood glucose level of under 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 refer a person to a dietician or another specialist.