GlaxoSmithKline PLC reported its first-quarter profit fell 13.7 percent from a year ago as sales of the group's main drug for diabetes Avandia fell.

Sales of Avandia slumped 56 percent as the U.S. Food and Drug Administration reported the drug could increase risks of heart attacks.

In general the company said profit decreased due to generic competition to its products. Profit fell 5 percent was 1.3 billion pounds the equivalent to $2.58 billion compared to 1.5 billion in 2007.

Revenue rose 1.6 percent to 5.69 billion pounds $11.3 billion

In the U.S market revenue fell 10 percent to 2.14 billion pounds.

Shares of Avandia fell 0.27 percent in after trading to $44.61 on the New York stock Exchange on Wednesday.