Nevertheless, drug firms are in hot pursuit of decoding Syndrome X's secrets, eyeing a potential patient pool of an estimated 70 million Americans who are insulin resistant.

FORBES: The Unknown Epidemic

To save themselves when they are threatened with being overwhelmed by lipids, cells become insulin-resistant, which stops them taking up extra glucose which would then be converted into lipids.

ECONOMIST: Metabolic syndrome

The researchers, led by Dr Lawrence Serfaty, found patients with severe OSA were more insulin-resistant and were more likely to have liver damage, compared to people of the same weight who did not have the sleep disorder.

BBC: NEWS | Health | Sleep disorder liver disease link