[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › Thiazolidinediones (glitazones)

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# Thiazolidinediones (glitazones)

Oral insulin sensitizers that act on a nuclear receptor in fat. They work slowly and can retain fluid and worsen heart failure.

Updated 2026-11-01

## What they are

PPAR-gamma agonists for type 2 diabetes. Pioglitazone is the one still widely used.

## Mechanism of action

Glitazones bind PPAR-gamma, a nuclear receptor that pairs with RXR and switches genes on, mostly in adipose tissue. Fat cells multiply and store more fatty acids, adiponectin rises and less fat reaches muscle and liver, so insulin sensitivity improves there. Because the action goes through gene transcription, the full effect takes weeks.

Target: Peroxisome proliferator-activated receptor gamma (PPAR-gamma, nuclear receptor)

## Key points

- Boxed warning: fluid retention that can cause or worsen heart failure; not started in NYHA class III–IV heart failure.
- Edema and weight gain; more fractures, especially in women.
- Pioglitazone: possible bladder cancer risk; rosiglitazone: debated heart attack risk and withdrawn in the US.
- Do not cause hypoglycemia alone; can restore ovulation in anovulatory women.
- Troglitazone was withdrawn for liver failure, so liver tests are checked.

## Drugs in this class

- [**Pioglitazone** An oral insulin sensitizer (PPAR-gamma agonist). It lowers glucose slowly without hypoglycemia, but retains fluid and… PPAR-gamma (nuclear receptor)](https://durgical.com/en/pharmacology/pioglitazone/)
- [**Rosiglitazone** A PPAR-gamma agonist like pioglitazone, now withdrawn from the US market and little used, because of heart failure and… PPAR-gamma (nuclear receptor)](https://durgical.com/en/pharmacology/rosiglitazone/)

## Others in the class

- troglitazone (withdrawn for liver failure)

## Test yourself

Think of the answer, then tap the question to see it.

## Why do glitazones take weeks to reach full effect?

They act through a nuclear receptor that changes gene transcription, and the new proteins and fat-cell changes take time to build up.

## Which patients should not start a thiazolidinedione?

Those with established NYHA class III or IV heart failure, because the drugs retain sodium and fluid.

## What partner does PPAR-gamma bind on DNA?

The retinoid X receptor (RXR); the pair binds response elements in target genes.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Pioglitazone: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a699016.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [DailyMed - PIOGLITAZONE HYDROCHLORIDE tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=04577c39-a9c0-4c66-a775-4c79e2c3dea5) (DailyMed (U.S. National Library of Medicine), 2026); [Crystal structure of Peroxisome proliferator-activated receptor gamma (PPARG)in complex with rosiglitazone](https://www.rcsb.org/structure/7AWC) (RCSB Protein Data Bank, 2020).

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Representative model, for educational purposes only.

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