Sulfonylureas for type 2 diabetes

Sulfonylureas are a group (or class) of medicines that work in a similar way. A sulfonylurea may be prescribed for people with type 2 diabetes as an alternative to metformin. More commonly, it will be used as well as metformin, if diet, exercise and metformin alone do not control blood glucose levels adequately.

The sulfonylureas include (active ingredient with brand names given in brackets):

Glibenclamide, gliclazide, glimepiride and glipizide are all active ingredients — the name of the chemical in the medicine that makes it work.

Note about medicine names

Most medicines have two names: the active ingredient and the brand name. The active ingredient is the chemical in the medicine that makes it work. The brand name is the name given to the medicine by its manufacturer. There may be several brands that contain the same active ingredient. This website uses active ingredient names, with brand names in brackets. We also discuss medicines in groups or ‘classes’, when their effects or actions are very similar.

To find out more, read our information about active ingredients and brand names.

What do sulfonylureas do?

Sulfonylureas lower blood glucose levels by increasing the amount of insulin made by the pancreas.

What are the benefits of taking sulfonylureas?

Sulfonylureas are commonly prescribed for diabetes. Their benefits and side effects have been observed for many years and are well understood, unlike newer medicines. Importantly, sulfonylureas have been shown to reduce the complications of diabetes, a very important benefit of these medicines.


  • reduce glucose levels in the blood
  • can be taken on their own by people who cannot take metformin.

Who can take a sulfonylurea?

  • People with type 2 diabetes.

However, sulfonylureas may not be suitable for everyone — in particular, they may not be suitable for older people, women who are pregnant or breastfeeding, people with ketoacidosis, or those with severe liver or kidney problems.

What are the side effects of sulfonylureas?

Common side effects of sulfonylureas include:

Hypoglycaemia is up to five times more likely with sulfonylureas than with any other oral diabetes medicine, particularly in older people, and people with liver or kidney problems.

Less frequent side effects include nausea, diarrhoea, headaches and allergic reactions.

Who can I ask about side effects?

If you are concerned that you may have had side effects related to a medicine, seek medical advice or call the Adverse Medicines Events (AME) line on 1300 134 237 from anywhere in Australia (Mon–Fri, 9am–5pm) to report and discuss possible side effects.


It is important to tell your health professional about all the medicines you are taking — including prescription, over-the-counter and complementary medicines (herbal, ‘natural’, vitamins and minerals) — as they may interact with diabetes medicines and affect your blood glucose levels. This may mean that your doctor will need to adjust your dose of the sulfonylurea, or make changes to your other medicines.

Some medicines are known to affect blood glucose levels. Click on the following links to view tables that list some of these medicines:

Apart from these, other medicines that may interact with sulfonylureas include*:

  • some antibiotics (e.g. chloramphenicol, rifampicin, sulfonamides and tetracyclines)
  • medicines that prevent blood clots (e.g. heparin and warfarin) may increase the hypoglycaemic effect
  • acetazolamide — used to treat glaucoma, epilepsy and swelling in the legs due to fluid retention or oedema
  • some medicines for depression or psychotic disorders
  • thyroid hormones
  • ACE inhibitors (e.g. captopril or enalapril) — used to treat high blood pressure (hypertension), and other heart and circulatory problems — may increase risk of low blood glucose and a lower dose may be needed
  • medicines for fungal and yeast infections (e.g. fluconazole, ketoconazole and miconazole)
  • allopurinol — used to treat gout
  • cimetidine — used to treat ulcers and reflux of stomach acid (gastric reflux)
  • bosentan — used to treat pulmonary hypertension.

*As there are often many different brands of one medicine, we have only listed the active ingredients of the medicines here. To find out more, read our information about active ingredients and brand names.

Phone for medicines information

Call Medicines Line on 1300 MEDICINE (1300 633 424) to get information about your prescription, over-the-counter and complementary medicines (herbal, 'natural', vitamins and mineral supplements) from a pharmacist. Your call will be answered by healthdirect Australia.