Glitazones for type 2 diabetes
‘Glitazones’ is the nickname given to a group of medicines called thiazolidinediones, which are used to treat type 2 diabetes. The glitazones are:
Pioglitazone and rosiglitazone are the active ingredients in these medicines.
Note: On 31 January 2017 one of the medicines containing rosiglitazone, Avandia, was discontinued by its manufacturer. If you were prescribed Avandia to treat your diabetes, see your health professional for advice on alternative treatments.
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.
The glitazones are effective at lowering blood glucose but have not been shown to reduce the long-term complications of diabetes (such as heart disease and stroke). This may become clear when they have been used by more people for longer periods of time.
Diabetes is a progressive condition. After a while, a single medicine will not be enough to control the levels of glucose in your blood. It could be months or years before this happens — but once it does another kind of diabetes medicine needs to be added to metformin (or a sulfonylurea) to control blood glucose levels.
Most commonly, people will start taking both metformin and a sulfonylurea when they need two medicines to control their blood glucose. However, some people can’t take this combination because they experience bad side effects, or they have a medical condition or another reason that means they can’t take metformin or a sulfonylurea (i.e. a contraindication). These people may have another kind of diabetes medicine added to their metformin (or sulfonylurea) instead.
The glitazones (pioglitazone and rosiglitazone) are one kind of diabetes medicine that can be used when this happens. Pioglitazone can be added to metformin or a sulphonylurea. Rosiglitazone can be added to metformin and is available as a combination tablet (Avandamet).
What do glitazones do?
Glitazones lower blood glucose levels by helping the body to use insulin better by reducing insulin resistance in the tissues of the body.
What are the benefits of taking a glitazone?
Pioglitazone may be taken on its own when diet and exercise alone don’t adequately control blood glucose levels. This may be a useful option, for example, if you are unable to take either metformin or a sulfonylurea.
Pioglitazone can also be given as a second medicine to people who are already taking either metformin or a sulfonylurea. Rosiglitazone can be given as a second medicine to people who are already taking metformin.
Pioglitazone can also be given to people who are already taking both metformin and a sulfonylurea if their blood glucose levels are still too high, and it can be used in combination with insulin.
Pioglitazone may reduce fats in the blood (triglycerides) more than rosiglitazone.
Note: Pioglitazone is only subsidised by the Pharmaceutical Benefits Scheme (PBS)if taken in combination with metformin and/or a sulphonylurea, or with insulin. Rosiglitazone is only subsidised in combination with metformin.
Who can take a glitazone?
- People with type 2 diabetes whose blood glucose is inadequately controlled by metformin or a sulfonylurea.
- Pioglitazone (Actos) can be given to people already taking metformin and a sulfonylurea and to people using insulin.
Glitazones may not be suitable for people with:
- oedema (swelling due to fluid) as glitazones can also cause fluid build-up
- liver problems or kidney disease
- eye problems caused by diabetes, such as fluid retention in the eye (diabetic macular oedema).
Glitazones are not suitable for people with:
- heart failure or at risk of heart failure
Rosiglitazone is not suitable for people with heart disease because it may increase heart attacks.
Pioglitazone is not suitable for anyone with bladder cancer or any who has had bladder cancer.
What are the side effects of glitazones?
Glitazones are known to commonly cause:
- muscle pain
- water retention and weight gain
- headaches and dizziness
- joint pain (arthralgia)
- hypoglycaemia (low blood sugar)
- lower iron (haemoglobin) levels in the blood.
Less frequently, bone fractures in women have been linked to glitazones.
In rare cases, glitazones can cause heart failure, liver damage, and fluid accumulation in the lungs (pulmonary oedema).
Rosiglitazone may increase the risk of a heart attack (myocardial infarction), fluid retention in the eye (diabetic macular oedema) that can affect vision, and increased levels of ‘bad’ LDL cholesterol.
Pioglitazone may slightly increase the risk of developing bladder cancer when used for more than 1 year.
Talk to your health professional if you have any concerns.
Click through the following links if you would like to read our brief information on pioglitazone written for health professionals.
Who else 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 the dose of your glitazone, 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 pioglitazone and rosiglitazone include:*
- some antibiotics (e.g. rifampicin and trimethoprim)
- ketoconazole — used to treat fungal infections
- gemfibrozil — a medicine given to some people to treat high cholesterol and fats (triglycerides) in the blood
- non-steroidal anti-inflammatory medicines (NSAIDs), with the exception of low-dose aspirin
- topiramate — used to treat epilepsy or migraine.
*As there are often many different brands of one medicine, we have only listed the active ingredient of the medicine 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.