How long it takes metformin to start working

Key takeaways

• Metformin is among the first drugs of choice for managing blood sugar levels in people with type 2 diabetes. It is sometimes used to treat conditions like PCOS, too.
• It takes metformin approximately three hours to start working after administration, about one week to reduce fasting plasma glucose (sugar level after eight hours of fasting), and about two months for the effect to be fully noticed and sustained.
• Avoid consuming alcohol when on metformin medication, as that can increase the risk of lactic acidosis (the buildup of lactic acid in the blood), which affects blood sugar levels. 
• If any concerns arise or side effects occur when taking metformin medication, consult a doctor.

Metformin is an oral medication that belongs to the class of drugs called biguanides. Healthcare professionals typically prescribe it for managing type 2 diabetes—a chronic condition that makes it difficult for the body to regulate blood sugar levels as it should. 

Metformin comes in both immediate-release and extended-release formulations. Immediate-release works quickly to reduce blood sugar levels and can be taken two to three times a day, while extended-release works slowly over a long period of time and is typically taken only once a day.

Studies suggest that metformin stands as the preferred first-line drug for treating type 2 diabetes in both adults and children who are ten years of age and older. Metformin is also beneficial in the treatment of other metabolic diseases, including polycystic ovary syndrome (PCOS). This article explains the duration it takes for metformin to work in several conditions and how it works.

Metformin works by: 

• Reducing glucose production by the liver
• Reducing the body’s absorption of sugar from consumed food
• Making the body more sensitive to insulin

Does metformin work immediately after taking it?

No, metformin does not work immediately after you take it.

It takes approximately three hours for metformin to start working after administration. Effects, such as proper lowering and stabilizing of blood sugar levels, are usually noticeable within the first week of taking the medication.  This applies to both metformin oral tablets and oral solutions.

According to research, there is no significant difference between immediate-release tablets, extended-release tablets, and metformin oral solutions in how they work. They all work the same way.

However, the time it takes for metformin to start working will depend on factors like the person’s dosage, the onset of action, the specific formulation, and the presence of food in the stomach. 

How long it takes metformin to lower blood sugar

Metformin does not instantly reduce blood sugar levels; typically, it begins to lower blood sugar levels within a week of starting treatment. 

According to research carried out on 706 people, metformin was discovered to lower blood sugar within the first week of treatment. However, it took about two months for it to have a complete and more sustained effect on blood sugar, and the blood sugar regulation was maintained for twenty-four weeks.

The effectiveness of metformin also depends on other factors, such as the individual's overall health, the severity of diabetes, and lifestyle factors like diet and exercise.

How long it takes metformin to work for PCOS

The time it takes for metformin to work in people with PCOS is not clear, although a study shows that metformin is likely to take longer to work on people with PCOS if taken alone as compared to when combined with other medications like clomiphene citrate.

Metformin is mostly prescribed for people with PCOS to help regulate menstrual cycles, lower insulin levels, and improve fertility. It may help reduce insulin resistance, decrease androgen  (male hormone) levels, and regularize ovulation.

It's important to note that to enhance metformin’s effectiveness in managing PCOS symptoms, it is best to combine this medication with dietary modifications and exercise.

How long it takes to lose weight on metformin

Metformin is not primarily prescribed as a weight-loss medication. However, some individuals may experience weight loss as a secondary effect of taking metformin.

It may take up to a year to lose 5% of body weight when taking metformin, and this varies among individuals. If weight loss occurs with metformin, it is typically gradual and moderate.

How long does it take metformin to lower testosterone levels?

It may take a few weeks or months for metformin to cause significant changes in testosterone levels.

According to a study carried out on male patients aged 18–60, it shows that metformin can reduce testosterone levels in people with type 2 diabetes when combined with insulin therapy. The study found that participants' testosterone levels decreased after three months of taking metformin, and this is often accompanied by improved blood sugar regulation.

How long it takes metformin to leave the body

It typically takes around five half-lives for a medication to be considered cleared from the body. The half-life of a drug is how long it takes for the body to get rid of half of a dose. 

Metformin has a half-life of approximately 6.2 hours. So, it would take around 31 hours (or roughly 1.3 days) for metformin to be completely cleared from the body.

Also, research indicates that about 90% of a metformin dose is cleared through the kidneys within 24 hours of taking it. This explains the importance of taking metformin doses daily for it to be effective.

However, it's important to remember that individual factors, such as metabolism, kidney functions, and other medications or medical conditions, can influence the time it takes for metformin to leave the body system. 

What to avoid while on metformin

When taking metformin, there are certain foods and medications you should consider avoiding or limiting their intake.

Foods to avoid while on metformin include:

• Limit alcohol consumption or avoid it altogether, as it can increase the risk of lactic acidosis and affect blood sugar control.
• Avoid consuming excessive amounts of sugary foods and drinks because they can affect blood sugar levels. It's generally recommended to eat a healthy diet that includes whole grains, lean proteins, fruits, vegetables, and moderate amounts of carbohydrates.
• Avoid the use of herbal remedies and complementary medicines that are not tested, like prescription and pharmaceutical medicines, because it's hard to tell the effect such medicines will have when taken with metformin. So, it is best to avoid taking metformin with them or talk to a doctor first before using them.

What to do while on metformin

Here are things to do instead while on metformin:

• Exercise regularly.
• Eat whole foods that contain healthy fats, protein, and carbohydrates (not refined carbs).
• Inform your healthcare professionals performing medical tests or procedures that involve the use of contrast agents, such as CT scans or angiograms, that you are taking metformin. In some cases, metformin may need to be temporarily discontinued before and after the procedure to reduce the risk of lactic acidosis.
• Inform your doctor about all the medications you are taking, including prescription drugs such as acetazolamide (Diamox), dichlorphenamide (Keveyis), and methazolamide.

What to do if metformin seems not to be working for you

If it seems like (or indeed) metformin is not working for you, here are things you can do:

• Examine your lifestyle habits, including diet and physical activity, to know if there are necessary changes you can make. 
• Schedule an appointment with a doctor or healthcare professional to discuss your concerns. The doctor may consider adjusting the dosage of metformin or exploring alternative treatment options based on your needs.
• Take metformin as prescribed and follow the recommended dosage instructions.
• Regularly monitor your blood sugar levels as directed by a healthcare professional. This will help track your response to metformin and determine if adjustments are necessary.
• In some cases, metformin alone may not be sufficient to manage diabetes. Your doctor may recommend additional medications, insulin therapy, or other treatment approaches to better manage blood sugar levels.

Final note

Metformin is mostly used for the management of type 2 diabetes. It works by reducing glucose production in the liver, improving insulin sensitivity, and helping to control blood sugar levels. 

Metformin typically doesn’t work immediately when a person takes it; it often takes about three hours to start working. People taking it for diabetes management may also notice stable results after about one week of commencing the medication therapy.

While its primary use is for diabetes, metformin may also have other potential benefits, such as modest weight loss and reductions in belly fat.

It is important to note that metformin should be used under the guidance of a healthcare professional, who will determine the appropriate dosage and monitor its effectiveness.