Shares in the world's biggest insulin producer Novo Nordisk plunged by up to 15 percent on Monday after the company said US drug authorities had rejected its applications for two new insulin treatments.
The Danish company said it had received a letter from the US Food and Drug Administration (FDA) stating "that approvals for Tresiba and Ryzodeg cannot be granted" until the company provides additional information.
The FDA requested more cardiovascular data, which Novo Nordisk said it was unlikely to be able to provide this year.
"We are surprised and disappointed to receive this letter, but we acknowledge this decision by the FDA and will work with the agency to determine the best path forward to completing the review," chief executive Lars Rebien Soerensen said in a statement.
"We are convinced that Tresiba and Ryzodeg offer significant benefits for people who require insulin," he said.
The two new products have been approved in the EU, Japan and Mexico and are under regulatory review in several other countries, the company said.
Shares in French pharmaceutical company Sanofi rose on Monday since its diabetes treatment Lantus is considered the main rival to Tresiba.
Novo Nordisk said the announcement wouldn't "significantly impact" its full year guidance.
Shares in the company -- a Copenhagen bourse heavyweight -- were down by 11.92 percent in mid morning trading, in a market that was 5.85 percent lower.