What Is Metformin?

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Metformin is a type 2 diabetes treatment that improves blood glucose levels and supports healthy weight management.

We take a look at this type 2 diabetes medication in greater detail below.

What is metformin?

Metformin is an oral medication that reduces the amount of glucose your liver produces, helping your body respond more naturally to the insulin it releases. It is commonly prescribed as a treatment for type 2 diabetes and gestational diabetes.

Metformin is available as a standard-release formulation; this is the recommended initial drug treatment for adults with type 2 diabetes, according to the National Institute of Clinical Excellence (NICE). You take the standard-release metformin two or three times a day, either with a meal or just after you’ve finished eating.

Metformin is also prescribed as a modified-release medication, which is gradually released into the bloodstream. This formulation can allow a simpler dosing regime and reduce gastrointestinal side-effects, so many patients find it more acceptable.

What does metformin do?

Metformin is an effective treatment for type 2 diabetes, particularly in people who are overweight or obese.

In combination with a healthy diet and exercise, metformin can help reduce blood glucose levels. Metformin can reduce diabetes complications and deaths by about thirty percent compared to other treatments, including insulin and oral sulfonylureas.

Metformin acts in several ways to decrease blood glucose levels:

  • Metformin is called an insulin sensitiser because it increases your body’s natural response to insulin
  • Metformin suppresses glucose production in your liver
  • Metformin decreases the absorption of glucose from food in your gastrointestinal tract
  • Metformin increases glucose disposal into your muscles

Metformin doesn’t work immediately to lower your blood sugar levels. The effect builds up gradually, taking up to five days to reach its full effect.

Metformin side effects

Metformin is used widely across the world and is considered a safe and effective medication. It is usually very well tolerated by patients. However, all medications have side effects.

The response to metformin can differ significantly between individuals. Your doctor may gradually increase your metformin dose to decrease the risk of problems; they may also prescribe a modified-release formulation which may reduce side effects in some people.

  • Gastrointestinal disturbance: Gastrointestinal problems, including nausea, abdominal pain, gas, bloating, and diarrhoea, are the most common side effects in people starting metformin therapy

There are a few ways of reducing any distressing GI disturbance: You can take the medication with a meal, you can reduce the carbohydrates in your diet, your doctor can initially start you on a low dose and gradually build up the quantity over time, or you could try a modified-release formulation.

  • Appetite loss
  • An unpleasant metallic taste in your mouth
  • Hypoglycaemia: Sometimes, metformin can decrease your blood glucose levels too far. This is more likely if you also take insulin or sulfonylurea medication; however, you may also have a hypo if you’re on metformin and drink too much alcohol
  • Anaemia: Metformin can block absorption of vitamin B12 and lead to anaemia, particularly after long-term use. The symptoms include severe fatigue, low energy, pins and needles, muscle weakness, a sore, red tongue, and disturbed vision.

You should contact your doctor, who may prescribe B12 supplements. You can also boost B12 in your diet by eating meat and liver, salmon and cod, egg yolks, poultry and dairy produce

  • Lactic acidosis: Very rarely, metformin can cause this condition where lactic acid accumulates in the blood. It can happen if metformin levels build up because of kidney problems, heart failure, or liver disease.
  • Hepatitis: See your doctor if your skin and the whites of your eyes become yellow
  • Skin rash: Contact your doctor if you experience redness, flushing and itching

Metformin and weight loss

Unlike many diabetes medications, which can cause weight gain, many people taking metformin experience weight loss.

Metformin is not licenced as a weight loss medication, but it can help obese people with type 2 diabetes lose weight and improve their diabetes control. Metformin may reduce appetite and decrease the number of calories you eat. This can result from the side-effects such as changes to taste, nausea, bloating and diarrhoea.

Metformin also lowers insulin levels helping to reduce hunger. However, metformin may also increase levels of the hormone leptin, so you feel full more quickly.

People taking metformin lost body fat with lower waist measurements and reduced waist-to-hip ratios, which is great for your metabolic health.

Foods to avoid on metformin

Metformin lowers your insulin levels and helps you lose weight. But metformin doesn’t replace a healthy diet. Eating foods that spike your blood sugar levels will counteract the beneficial effects of the medication.

Choosing a healthy diet low in sugar and carbohydrates, especially processed carbohydrates, will help you lose weight, control your blood glucose levels and reduce the complications of diabetes. Foods to avoid include:

  • Sugar and other high GI foods: GI The Glycaemic Index or GI is a way of ranking foods according to how quickly their energy is released into the bloodstream and their effect on blood glucose.

Foods that are absorbed slowly have a low GI rating, while foods that are processed more quickly have a higher rating. It runs from 0-100, with simple glucose scoring the whole hundred.

The carbohydrates that absorb slower have a GI rating of 55 or below. This includes most fruits and vegetables, unsweetened dairy products, many wholegrain cereals and bread products, as well as nuts, beans and pulses.

Try to stick to low GI food and avoid sweets, cakes, biscuits and processed white carbohydrates.

  • Salt: Too much salt in your diet can increase your blood pressure. However, salt isn’t just in the shaker. It’s hidden in processed and prepared foods, including sauces, bread, cured meats and breakfast cereals.
  • Unhealthy fats: Fat is an essential part of your diet, but try to avoid too much saturated fat from butter, cheese and cream. Instead, choose healthy fats from seeds, nuts, oily fish and avocado.

Diabetes UK says:

Eating to control your diabetes isn’t just about GI ratings. Think of the bigger picture and choose foods low in saturated fat, salt and sugar as part of a healthy, balanced diet.

The London Diabetes Centre is on hand to help. If you have any questions about metformin not covered in this article or, you are looking for advice or treatment options for a loved one, get in touch today.



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