Shares in Novo Nordisk have taken a dip as the firm acknowledged that US regulators could demand stronger warnings on its investigational diabetes drug liraglutide.

The Danish company was speaking after the US Food and Drug Administration called for tougher warnings on Amylin’s glucagon-like peptide-1 analogue Byetta (exenatide) about the risk of acute pancreatitis after two patients died. Liraglitude, which is also a GLP-1 analogue, was filed for regulatory approval in the USA and Europe earlier this year.

However Novo's chief scientific officer Mads Krogsgaard Thomsen told a number of news services that although there had been cases of pancreatitis in patients treated with liraglutide, the firm has not seen a statistically significant increased frequency in patients on the drug. He added that diabetics are already at increased risk of pancreatitis compared with healthy patients.

The pancreatitis issue comes just after advisors to the FDA recommended that the agency require drugmakers to conduct long-term trials of new diabetes treatments to evaluate cardiovascular risks. This could delay the launch of any products by up to three years but Novo believes there will be no need for a cardiovascular study before liraglitude is approved.

The effect of all this has been to dampen the hype over GLP-1 analogues and analysts are looking at possibly reducing their sales forecasts on liraglitude if it does manage to get past the regulators. Forecasts range wildly from $1 billion up to around $6 billion, depending on whether it gets approval for the additional indication of obesity.