Avandia works by hitting a drug target called the peroxisome proliferator-activated receptor (PPAR) gamma.

FORBES: Open-Source Drug Safety?

Among those PPAR drugs in development, Merck's MK-767 was believed to be farthest along.

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The first PPAR drug, Rezulin from Pfizer (nyse: PFE - news - people ), was pulled from the market in 2000 because of liver side effects.

FORBES: Open-Source Drug Safety?

Eli Lilly (nyse: LLY - news - people ) and GlaxoSmithKline (nyse: GSK - news - people ) have a whole slate of PPAR drugs in development, all of which seem to work at least a little differently.

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Patients with a mutant version of the PPAR gamma gene have a 25% higher risk of developing adult-onset diabetes, in which cells stop responding to insulin's orders.

FORBES: Silencing "Syndrome X"

Existing diabetes drugs, such as Actos from Eli Lilly (nyse: LLY - news - people ) and Avandia from GlaxoSmithkline (nyse: GSX - news - people ), resensitize the body to insulin by turning on the PPAR gamma receptor.

FORBES: Silencing "Syndrome X"