Metformin is a medication commonly used to help people with type 2 diabetes look after their blood glucose levels. It belongs to the class of medications called Biguanides which include brand names such as Diabex, Diabex XR, Diaformin, Diaformin XR, Formet, Glucobete, Glucomet, Glucophage, Metex XR, and Metforbell.

Metformin helps to lower blood glucose levels by:

  • Reducing the amount of stored glucose released by the liver
  • Slowing absorption of glucose from the gut (intestine)
  • Helping the body to become more sensitive to insulin so that your own insulin works better

Metformin is the first choice medication to help people with type 2 diabetes look after their blood glucose levels and may be combined with other classes of tablets and/or insulin. Type 2 diabetes is a progressive condition which means over time it can become more difficult to look after your blood glucose levels, therefore Metformin may need to be increased or used in combination with other medications.

Like any medication, Metformin has the potential to cause side effects which could include nausea, diarrhoea, constipation, bloating, indigestion and/or a metallic taste in the mouth. To reduce these side effects Metformin should be started at a low dose and gradually increased. It should always be taken with or directly after a meal.

People with severe liver, kidney or heart disease are generally not prescribed Metformin.

Metformin may need to be stopped before and immediately after surgery or procedures that require a radio-opaque dye, such as coronary angiogram. You should always check with your doctor.

Long term use of Metformin may cause Vitamin B12 malabsorption which can lead to deficiency. Most GP’s will screen for Vitamin B12 deficiency however it is not routine, therefore if you think you are at risk, especially if you have been taking Metformin for several years, it is advisable to discuss this with your doctor or health care team.

The risk of developing Metformin associated vitamin B12 deficiency increases with age, dose and duration of use. Elderly people taking Metformin have a higher incidence of Vitamin B12 deficiency due to problems with absorption from the gastrointestinal tract and should therefore be tested regularly.

If low levels of vitamin B12 remain for a long time, the condition can lead to irreversible nerve damage which can cause numbness and tingling in the hands and feet, which may be mistaken for peripheral neuropathy caused by diabetes.

Some of the benefits of taking Metformin, along with looking after your diabetes, include possible weight loss and decreased appetite, and a low risk of hypoglycaemia (low blood glucose level). Metformin has also been shown to reduce overall death rate of people with type 2 diabetes.