Benefits of Metformin – Is It a Wonder Drug?
Medically reviewed by Dr Sultan Linjawi, Endocrinologist & Diabetes Specialist — December 2025
Metformin
Metformin belongs to a family of medications called biguanides. Metformin is the generic name of the drug. There are many brand names. Brand names of metformin include: Glucophage; Glucophage XR; Diaformin; Diabex; Fortamet; Glumetza; Riomet.
Metformin is the number one drug of choice by doctors to commence when someone is diagnosed with type 2 diabetes. It is considered the first line of therapy.
Why is this? Working to improve the ways our natural insulin works in our body and helping to regulate blood sugars by its action on the liver, metformin also has been associated with no hypoglycaemia (low blood sugars); no weight gain (and some studies even suggest weight loss) and is generally well tolerated.
It is one of the most affordable diabetes medications available and is increasingly being researched as it seems to have a number of other beneficial effects, playing a role in heart health, stroke prevention, cancer and general anti-ageing (Benefits of Metformin - read more below). Originally deriving from a plant, the French lilac, metformin has been around for a very long time, centuries in fact, and in its current tablet form since the 1970’s.
Introducing changes to your diet and exercise in combination with metformin have the biggest benefits in regulating blood sugars. Sometimes Metformin is started in pre-diabetes to try and halt the progression to diagnosis and also in gestational diabetes, with or without insulin. It is commonly given in combination with other diabetes medications if blood sugars are not within normal range.
What is Diabetes?
Type 2 diabetes is an elevation in blood sugars that occurs when a sugar, called glucose, can’t get into your fat and muscles where it is needed. Elevated blood glucose damages the lining of blood vessels leading to a range of complications in various organs of the body.
High blood glucose is sometimes referred to as high blood sugar. Diagnosing diabetes is done by measuring your blood sugar levels.
To learn more and what type 2 diabetes is, you can read more from our dedicated Type 2 Diabetes Mellitus page.
Since metformin is the number one drug of choice for people with type 2 diabetes, keep reading to learn more about metformin, including the benefits of metformin, and the side effects of metformin, for example diarrhoea.
The Benefits of Metformin
Metformin has been in the news quite a bit recently… Its’ been heralded as the answer to anti-ageing with major benefits to our health including our heart, stroke prevention and even warding off cancer. It does have side effects initially for about 10% of users (mainly diarrhoea and nausea), but if affected should only last a couple of weeks, is it worth it?
Read on to find out what we know so far.
Cancer Prevention
Metformin does not actually stimulate insulin production but instead works on the cells in our body to make them more sensitive to our own insulin that we produce to help regulate levels of blood glucose. It also works on the liver to reduce the amount of glucose it releases into the bloodstream. A third way that Metformin works is by having a direct effect on the gut to slow down the absorption of glucose from the food that we eat. The fact that Metformin does not actually stimulate insulin production means that it is not causing an increase in the amount of insulin produced in the body which is good news indeed. As insulin is a natural growth hormone it has been linked to an increase in cancers along with obesity which increases the need for insulin in the body.
Recent studies (New Users of Metformin Are at Low Risk of Incident Cancer by Libby et al and Metformin Associated With Lower Cancer Mortality in Type 2 Diabetes ZODIAC-16) observed that people on metformin had about half as many incidences of cancer than those not taking the drug. It is thought that this affect is a result of minimising DNA damage by decreasing reactive oxygen in our cells, effectively acting as a powerful antioxidant in preventing tumour growth. As these studies have only examined cancer risk retrospectively, large clinical trials are now underway such as the Targeting Aging with Metformin (TAME) in the USA which is collecting data over a 5-year period not only looking at the occurrence of cancers but also cardiovascular events, dementia and deaths. However, from the evidence we have so far is seems that metformin is useful in the prevention and possibly even treatment of cancers.
Cardiovascular Benefits
A very important trial which ran over 10 years, The United Kingdom Prospective Diabetes Study (UKPDS) (Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes (UKPDS 34)) found that obese patients who were given metformin had fewer cardiovascular events than those who were given alternative drugs for diabetes (sulphonylurea or insulin) as initial treatment. This has been further backed up by other studies (Long-term Effects of Metformin on Metabolism and Microvascular and Macrovascular Disease in Patients With Type 2 Diabetes Mellitus) including one which compared metformin with a placebo which indicates that metformin use is linked to a reduction in heart attacks; heart failure and strokes. It also has a positive effect on cholesterol levels further enhancing these heart protective qualities.
Weight Loss
Although it is usually referred to as being a ‘weight neutral’ medication, some studies suggest that with many patients there is some weight reduction when taking metformin (Weight Management in Type 2 Diabetes: Current and Emerging Approaches to Treatment).
Dementia
In the systematic review, (Metformin Use Associated with Reduced Risk of Dementia in Patients with Diabetes: A Systematic Review and Meta-Analysis) it was suggested that metformin may play a role in neuroprotection and preservation of cognitive function in people with diabetes. More data is still required, however. It is important to note that metformin should not be used by individuals without diabetes for the prevention of dementia as there is no evidence to support this use.
Anti-Ageing
Even though we are waiting for the completion of studies such as TAME (Metformin as a Tool to Target Aging) to find out whether metformin can really delay the onset of age related diseases the evidence is building and metformin can indeed be seen to have many beneficial effects other than regulating blood glucose levels.
It appears that the longer the user is on metformin the greater these effects are and that it could actually extend your life (Metformin: Do we finally have an anti-aging drug?). As it is also an inexpensive drug it is now considered to be first line therapy for those diagnosed with type 2 diabetes but may also be of benefit to those without diabetes.
If you’re starting metformin — or you’ve been taking it and still feel unsure about it — Dr Sultan has created this clear, practical guide to help you understand what it’s doing and what to expect.
How metformin is usually started
One of the most important things to understand about metformin is that starting slowly matters. Many side effects are related not to the medication itself, but to how quickly it is introduced.
Metformin is typically started at a low dose and increased gradually over several weeks. This allows the digestive system time to adapt. Taking metformin with meals also reduces stomach upset.
Some people are prescribed an extended-release (modified-release) form, which releases the medication more slowly and is often easier to tolerate.
If you would like a practical, step-by-step overview of how metformin is usually started, including dose increases, timing with meals, and what to do if side effects occur, we’ve created a short, specialist-written guide you can download.
Free metformin starter guide:
A clear, practical explanation of how doctors usually introduce metformin safely in real life
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Frequently Asked Questions
What is metformin?
Metformin is a first-line oral medication for type 2 diabetes. It helps lower blood glucose levels by reducing the amount of glucose produced by the liver and improving the body’s response to insulin.
How does metformin work?
Metformin decreases hepatic (liver) glucose production, improves insulin sensitivity, and reduces glucose release into the bloodstream. In some people it can also modestly improve cholesterol and triglyceride levels.
What are the benefits of metformin?
Metformin helps improve glucose control, is generally weight-neutral, may support small weight reductions in some people, and is low cost and well studied. For many adults, it forms the foundation of long-term diabetes treatment.
How should I take metformin?
Metformin is typically started at a low dose, such as 500 mg once daily with food, and increased gradually over one to two weeks to reduce stomach upset. Usual doses range up to 2,000–3,000 mg per day depending on the formulation and your clinician’s advice.
What are the side effects of metformin?
Common side effects include diarrhoea, nausea, abdominal discomfort, and a metallic taste—especially when treatment begins. Long-term use may reduce vitamin B12 levels. Speak with your clinician if symptoms persist or worsen.
Can I drink alcohol while taking metformin?
Alcohol should be consumed in moderation. Excessive drinking increases the risk of side effects including lactic acidosis. Alcohol can also lower blood glucose and increase hypoglycaemia risk when used with certain medications.
Can metformin be taken during pregnancy?
Metformin is used in some pregnancies, including gestational diabetes, depending on local guidelines and clinician advice. Diabetes management in pregnancy should always be individualised and closely supervised.
When should I avoid taking metformin?
Metformin may not be suitable for people with severe kidney impairment, significant liver disease, dehydration, or medical conditions that reduce oxygen delivery to tissues. It may also need to be paused around surgery or contrast imaging. Follow your clinician’s instructions.
Why does metformin cause diarrhoea?
Gastrointestinal upset is common when starting or increasing the dose. Taking metformin with meals, using gradual dose titration, or switching to an extended-release version often improves tolerance. Symptoms usually settle within days to weeks.
Why should I take metformin?
Metformin is an effective, well-researched starting therapy for type 2 diabetes. It improves glucose control, may delay the need for additional medication, and has a long safety record. Your clinician will confirm whether it is suitable for you.
