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Have you been prescribed Metformin for diabetes? Let's learn about this type of medication (Biguanides)!

MBBS
Medically Reviewed by MBBS ✓ Medically Reviewed
📅 Updated: Jul 14, 2026 • ⏱ 8 min read • Editorial policy
Have you been prescribed Metformin for diabetes? Let's learn about this type of medication (Biguanides)!
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When your doctor tells you that you have diabetes, the first thing you might be prescribed is a pill called Metformin. Today, we will talk simply and clearly about this common drug that is prescribed to many people for Type 2 Diabetes, not only in Sri Lanka, but also around the world. We will look at everything from what it is, what it does to the body, and what we need to be careful about.

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What are biguanides? Is it the same as metformin?

Simply put, Biguanides are the name given to a group of drugs used to treat diabetes. Just like there are types of vehicles. Just like there are types of cars, vans, and buses, there are different groups of diabetes drugs. Biguanides are one such group.

Currently, the only drug used in this category in most countries of the world is Metformin . This means that if you take Metformin, you are taking a drug that belongs to the Biguanide class. This is a drug that is taken orally in the form of a tablet. This drug can come under different brand names such as Glucophage®, Fortamet®, but they all contain Metformin.

What conditions is Metformin used for?

The main and officially approved use of metformin is to control type 2 diabetes . In fact, metformin is often the first-line therapy that doctors start for type 2 diabetes.

But in addition, doctors also prescribe this drug for a number of other health conditions. This is called "off-label" use. That is, the drug is given for other beneficial uses than those for which it was originally approved.

Other uses of Metformin A simple explanation
Gestational Diabetes Control diabetes that occurs in some mothers during pregnancy.
Prediabetes Control blood sugar levels in people at risk of developing diabetes and delay or prevent the development of diabetes.
Polycystic ovary syndrome (PCOS) Helps regulate hormonal imbalances and menstrual cycles in women with PCOS.
Some psychiatric medications cause weight gain Control weight gain caused by medications for some mental illnesses.

In addition, some studies have found that people taking metformin may have a reduced risk of developing cancer, but this is still in the research stage.

How does this Metformin drug work inside the body?

Metformin helps control our body's sugar levels in two main ways.

1. Reduces the amount of sugar added to the blood by the liver: Normally, our liver releases sugar (glucose) into the blood for energy. Metformin controls this process and reduces the unnecessary accumulation of sugar in the blood.

2. Increases Insulin Sensitivity in Muscles: One of the main functions of the hormone insulin in our body is to help the cells take in sugar from the blood and use it for energy. In diabetes, this process is impaired. Metformin makes our muscles respond better to insulin. Then, the muscles can easily absorb and use the sugar in the blood.

Both of these methods help control high blood sugar levels. In PCOS, this medication lowers insulin levels, which in turn helps balance hormones and regulate the menstrual cycle.

What are the main benefits of Metformin?

  • Better diabetes control: Studies have shown that metformin can reduce your HbA1c test value, which shows your average blood sugar levels over the past three months, by about 1% .
  • Preventing diabetes: It has been found that taking Metformin along with lifestyle changes can reduce the risk of developing diabetes by about 31% in people with prediabetes.
  • Reduced risk of heart disease: Some studies suggest that metformin may reduce the risk of heart disease and related complications (cardiovascular disease).

Are there any side effects to this medicine?

Yes, like all medications, Metformin can cause some side effects. However, for most people, these only occur when they first start taking the medication and then go away as the body adjusts to it.

Side effect Learn about this
Common side effects that many people may experience
Indigestion, diarrhea This is the most common side effect. It usually goes away within a few days. You can reduce this by taking the medicine with food.
Nausea and vomiting This is also common in the early stages.
Rare side effects
Chest discomfort, headache, excessive sweating (diaphoresis), and feeling lethargic. These are not common, but if you continue to have these symptoms, tell your doctor.
Low blood sugar (Hypoglycemia) This is less likely to happen if you take metformin alone, but it can happen when you take it with other diabetes medications.

What are the specific risks to be aware of with metformin?

Metformin is generally a very safe medication. However, there are some specific risks that we should all be aware of.

Vitamin B12 Deficiency

Metformin for a long timeWhen used, the body's absorption of vitamin B12 may be slightly reduced. Therefore, your doctor may check your vitamin B12 levels and, if necessary, prescribe a vitamin B12 supplement.

Lactic Acidosis

This is the most important thing everyone should be aware of when talking about Metformin. But first, it should be said that this is a very rare , but serious condition that can even be life-threatening if it occurs. About one in 30,000 people taking Metformin has this risk.

  • What is Lactic Acidosis? Simply put, it is the unnecessary accumulation of a chemical called lactic acid in the body.
  • Who is more at risk for this?
  • For those with kidney or liver disease.
  • For those over 65 years of age.
  • For those who have recently undergone surgery.
  • For those who drink alcohol excessively.
  • Symptoms of Lactic Acidosis:
  • Sudden extreme fatigue and weakness.
  • Nausea, vomiting, and stomach pain.
  • Rapid breathing or deep, prolonged breathing.

Warning: If you are taking Metformin and experience one or more of these symptoms, go to the nearest hospital emergency department (ETU) immediately. This is not something to delay.

Drug Interactions

If you are taking Metformin, it is very important to tell your doctor about all other medications you are taking (including medications for other conditions, vitamins, and even nutritional supplements). Some medications can increase the risk of lactic acidosis or low blood sugar (hypoglycemia) when taken with Metformin.

When should I talk to the doctor?

If you are taking Metformin, it is important to see your doctor regularly to make sure the medication is working and that your blood sugar is under control. In addition, talk to your doctor about these things as well.

  • If the side effects are too much for you to handle.
  • If you feel like your conditions like diabetes or PCOS are not being properly controlled despite taking medication.
  • If you feel like you need to stop taking this medicine ( never stop taking medicine without asking your doctor ).

💡 Take-Home Message

  • Metformin is a very common, safe, and effective medication for type 2 diabetes.
  • This mainly works by reducing sugar production by the liver and increasing insulin sensitivity in muscles.
  • Common side effects, such as bloating, may occur initially and then disappear as the body adjusts.
  • Lactic Acidosis is a rare but serious condition. Be aware of its symptoms and go to the ETU immediately if you experience any of these symptoms.
  • It is imperative to inform your doctor about all other medications you are taking.
  • Never stop taking Metformin without medical advice. If you have any questions, don't hesitate to ask your doctor.
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⚠️ Important: Medical articles and information on Nirogi Lanka are strictly for educational and awareness purposes and do not substitute professional medical advice, diagnosis, or treatment. Always consult a qualified physician for any medical concerns.