GlaxoSmithKline Plc has been allegedly withholding a study showing that its Avandia diabetes drug may cause heart attacks, according to two people having the knowledge of a lawsuit filed against the drug maker.

Dr. Rosemary Johann-Liang, the former U.S. Food and Drug Administration official, has claimed that a study in 2001 had discovered that Avandia posed an augmented heart-attack risk than adversary medicines.

Glaxo also hadn’t reverted to an e-mail from researchers who had concluded that Avandia reinforced the signs of heart ailments.

Johann-Liang affirmed that FDA officials had provided the drugmaker with particulars of internal agency deliberations about grousing up the warnings.

To judge whether Avandia’s knack to control blood-sugar levels outweighed a probable augment in heart attacks, strokes and deaths from cardiovascular disease, Johann-Liang’s authentication would be measured by an FDA advisory panel meeting next week in Washington.

While Glaxo officials argue that no studies had proven that Avandia was unsafe, drug-safety advocates have called for the medicine’s removal from the market.

Mary Anne Rhyne, a Company spokeswoman, disputed Johann-Liang’s claims that it hadn’t turned over a 2001 review of Avandia’s health risks to federal regulators.

Rhyne said that the Company’s study “determined that there was no signal of an increased risk for heart attacks associated with Avandia. GSK identified this internal review and described its results in a Periodic Safety Update Report that was submitted to the FDA”.