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Thiazolidinediones

Medically Reviewed.Last updated on 01/14/2026.

Thiazolidinediones are a class of drugs to treat Type 2 diabetes. They work by helping your body use insulin more efficiently. This helps you manage blood sugar levels. Your healthcare provider can discuss your options and the pros and cons.

What Are Thiazolidinediones?

Thiazolidinediones (TZDs and glitazones) are a class of medications that treat Type 2 diabetes by improving insulin sensitivity, lowering glucose levels and helping reduce fat stored in your liver. TZDs come as tablets that you swallow, typically once per day.

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This medication is also used off-label to treat polycystic ovary syndrome (PCOS). It may help with cirrhosis, too, if you have metabolic dysfunction-associated steatotic liver disease (MASLD).

How do thiazolidinediones work?

TZDs help your body use insulin more efficiently. They work by acting on PPAR-γ receptors in your fat, muscle and liver cells that control metabolism. When these receptors are activated, they can respond better to insulin. These cells become better at taking sugar from your blood. This means your blood sugar levels will decrease. They also help your liver produce less sugar.

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What are the different types of thiazolidinediones?

Pioglitazone (Actos™) and rosiglitazone (Avandia®) are the two types of TZDs. You typically take them in the following doses:

  • Pioglitazone: A dose of 15 to 30 milligrams (mg) once daily. The maximum dosage is 45 mg per day.
  • Rosiglitazone: A dose of 4 mg once daily. The maximum dose is 8 mg per day.

Always take thiazolidinediones as prescribed. If you think your dosage isn’t working, tell your provider. Some signs that you aren’t on the right dose include:

  • Consistently high blood sugar readings
  • Diabetes symptoms like feeling very thirsty, tired and peeing frequently

What happens if I miss a dose?

If you miss a dose, try to take it as soon as you remember. This is usually OK unless you’re within a few hours of your next scheduled dose. For example, if you typically take your medication with breakfast and remember at lunch, it’s OK to take it then. Don’t ever take two doses at once.

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What are the risks and side effects of thiazolidinediones?

Some of the side effects of taking these medications are:

  • Swelling in your legs and ankles
  • Weight gain

Taking TZDs can increase your risk of the following:

  • Broken bones
  • Heart failure
  • Liver damage
  • Bladder cancer (pioglitazone only)
  • Low blood sugar (especially if combined with other diabetes medications)

What are the benefits of thiazolidinediones?

The main benefit is that they control blood sugar levels. They also help your body respond better to insulin. There’s evidence that pioglitazone can improve cholesterol levels and help improve fatty liver.

They also work well with other diabetes medications. You can take TZDs with metformin, insulin injections and sulfonylureas.

Who shouldn’t take thiazolidinediones?

Anyone over 18 with Type 2 diabetes can take thiazolidinediones.

You shouldn’t take TZDs if you’re pregnant or thinking of becoming pregnant. You may not be able to take this medicine if you have:

  • Liver disease
  • Kidney disease
  • Bladder cancer or blood in your pee
  • Heart failure

Always talk to your healthcare provider before starting new medications. Be sure to tell them your full medical history, as well as any other medications and supplements you take.

A note from Cleveland Clinic

If you have Type 2 diabetes, TZDs may be one of the medications your healthcare provider recommends to manage your blood sugar. There are different thiazolidinediones available, but they work in the same way.

The medicine you use to keep your blood sugar in a healthy range is just one part of your diabetes management plan. Eating nutritious foods and staying active is also a part of your treatment. Always contact your healthcare provider if you have questions about your diabetes medication.

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Experts You Can Trust

Medically Reviewed.Last updated on 01/14/2026.

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References

Cleveland Clinic's health articles are based on evidence-backed information and review by medical professionals to ensure accuracy, reliability, and up-to-date clinical standards.

Care at Cleveland Clinic

Type 2 diabetes can affect your life in many ways. At Cleveland Clinic, we can help develop a treatment plan that matches you and your goals.

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