West Suffolk Diabetes Service


Drugs and New Products

 

Metformin

  What is Metformin?

  How does it work?

  What are the benefits of Metformin?

  What are the disadvantages?

  What is Lactic Acidosis?

  What are the warning symptoms of Lactic Acidosis?

  What precautions should I take?

  What if I become pregnant?

  Who should not take Metformin?

  How much do I need to take?

What is Metformin?

Metformin is a drug used to control type 2 diabetes. It is a member of a group of drugs known as biguanides, has been in use for many years and is known to be a safe and effective form of treatment. 

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How does it work?

Metformin works by reducing the amount of glucose produced by the liver and increasing the uptake of glucose by the cells of the body. This has the overall benefit of reducing blood glucose levels by 3-4 mmol/l. It does not increase how much insulin is made by the pancreas.

Metformin is also thought to help by lowering component of blood fats, that are often high in people with type 2 diabetes. 

Metformin also decreases the appetite and helps you lose a few pounds in weight.

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What are the benefits of Metformin?

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What are the disadvantages?

The most difficult problem with Metformin is due to its effect on the gastrointestinal system. They cause a wide range of effects from a mild loss of appetite to nausea, vomiting, abdominal discomfort, cramps, flatulence and diarrhoea. Some people describe a temporary unpleasant or metallic taste when they start taking Metformin.

If you do experience stomach upset, it is desirable that you try to persevere with Metformin, even if you find you can only tolerate one or two tablets daily.

Many patients find these symptoms impossible to cope with and discontinue the tablets within days. Others find the effects tolerable and find they improve with time. Starting off with a small dose taken at meal times helps.

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What is Lactic Acidosis?

Lactic acidosis, is a rare but dangerous side effect of Metformin.  This is a serious condition where the cells of the body do not get enough oxygen to survive. It is caused by a build up of lactic acid in the blood. Most of the cases described have been in people whose kidneys were not working normally. Although rare, if lactic acidosis does occur, it may be fatal in up to half the cases.

Your doctor will monitor your kidney function and carry out blood tests from time to time.

There is no evidence that  Metformin causes any damage to your kidneys or liver.

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What are the warning symptoms of Lactic Acidosis?

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What precautions should I take?

If you have an illness that results in severe vomiting and diarrhoea and if your intake of fluids is reduced, it may be necessary to stop taking Metformin temporarily. It is also usual to stop Metformin if you develop a serious condition such as a heart attack, stroke or severe infection.

If you are going to have surgery or have specialised x-ray procedures that require injection of contrast agents, Metformin should be stopped temporarily.

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What if I become pregnant?

Ideally you stop oral medications before planning your pregnancy. If pregnancy is confirmed unexpectedly you should stop taking Metformin as with other oral hypoglycaemic medications. Your doctor will probably change you over to insulin.

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Who should not take Metformin?

Metformin is not recommended for the people with the following conditions

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How much do I need to take?

The usual starting dose of Metformin is 500mg twice daily. Take the tablets with food or just before or after a meal. This may be increased by your doctor to  500 mg three times daily up to a maximum dose of 6 tablets (3 gm) each day. With Metformin it is sometimes useful to start with just one tablet each day until your stomach gets accustomed to your new tablets.

 

Dr. Nishan Wijenaike, Consultant Physician
2002 West Suffolk Hospitals Diabetes Service
October 2002

 

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Source: www.DiabeteSuffolk.com

Copyright: West Suffolk Hospitals NHS Trust, Hardwick Lane,
Bury St Edmunds, Suffolk IP33 2QZ, tel:01284 713000