When particularly bad news about a medication makes the news, a decline in stock prices for the drug's manufacturer may well follow. With diabetes drugs, this has happened at least three times in the past few years.
* Sanofi-Aventis, the maker of Lantus, a form of insulin, saw its shares slump in late June, after four observational studies suggested that the drug might be tied to an increased risk of cancer.
* Shares of GlaxoSmithKline fell 13 percent during a nine-day period in 2007, because of concern about heart risks that researchers linked to Avandia.
* Takeda Pharmaceutical Co. saw its shares drop in late June after the company said it expects a delay until 2012 in getting Food and Drug Administration approval of a diabetes drug called alogliptin. The FDA has asked Takeda to conduct a clinical trial to assess the drug's cardiovascular safety.