GlaxoSmithKline continued to suffer sharp falls in sales of Avandia, its diabetes drug, in the first quarter of 2008 as it reported operating profits down 9 per cent to £1.96bn.

The group said on Wednesday it was on track to meet guidance for the year that it gave with 2007 results in February. Then it said earnings per share, on its “business performance” basis would fall by a “mid-single digit percentage” in 2008.