All about Metformin


What is metformin?

Metformin is one of the most frequently prescribed oral medications for type 2 diabetes treatment. It may be prescribed to the newly diagnosed as the first line of treatment prior to insulin. Metformin is listed under various names, including Metformin XR. 

The drug belongs to the family of biguanides which increase insulin sensitivity and therefore have a beneficial effect in blood glucose management, particularly in insulin resistance. The biguanides started to be used in the 50s. As previously mentioned, it is perhaps the oral drug more prescribed in the world for type 2 diabetes treatment and its use is currently being studied in patients with type 1 diabetes. In 1998 the famous study (UKPDS) demonstrated the effects of metformin. It is currently used in combination with other oral drugs and can be prescribed to be used with insulin.

How does metformin work?

These drugs reduce the amount of glucose produced by our body, specifically in our liver and also improves the response that it has to insulin. Remember that in the case of type 2 diabetes, production of insulin is insufficient or does not have an adequate response.

Side effects of metformin

The side effects are generally gastrointestinal discomfort, including:

  • Nausea
  • Diarrhea
  • Lack of appetite
  • Stomach ache
  • Inflammation
  • Flatulence
  • Metallic taste in the mouth, among others

 These symptoms can go away on their own, however, you may want to consider seeing your doctor to receive additional treatment. 

Metformin is not recommended for use in the following cases:

  • You have unstable and/or insulin-dependent (type I) diabetes
  • You have metabolic acidosis (including diabetic ketoacidosis, with or without coma history of ketoacidosis
    with or without coma)
  • You have a history of lactic acidosis (too much acid in the blood)
  • You drink a lot of alcohol (regularly drink alcohol or sometimes drink a lot of alcohol, binge drinking)
  • You have liver or kidney problems (severe liver dysfunction or liver disease, or kidney disease or
  • You are going to have an x-ray procedure with injection of dyes (iodinated contrast materials)
  • You are stressed, have a severe infection or, are experiencing trauma
  • Before surgery and during your recovery after your surgery
  • You suffer from severe dehydration (have lost a lot of water from your body)
  • You are hypersensitive (have a high blood pressure) or allergic to metformin hydrochloride or any ingredient
    in the formulation or component of the container
  • You are pregnant or planning to become pregnant
  • You are breastfeeding (nursing a child)
  • You have cardiovascular collapse (abrupt failure of blood circulation) or a disease that can cause hypoxemia
    (low oxygen in the blood) such as cardiorespiratory insufficiency

Metformin isn’t the only drug available for people with type 2 diabetes, in fact, there are other drug classes specifically for people with type 2. 


  1. Inzucchi SE: Oral antihyperglycemic for type 2 diabetes. Scientific Review. JAMA 2002;287:360-372. 2.
  2. Roses J, Streets J, Friege F, Lara E, et al. Consenso de prediabetes (Prediabetes consensus). Document about the ALAD’s stance. Rev ALAD 2009; 146-158.

Written By Beyond Type 2 Editorial Team, Posted , Updated 09/02/23

This piece was authored collaboratively by the Beyond Type 2 Editorial Team.