In the following video, Motley Fool health-care analyst David Williamson highlights a potential new threat to an entire class of multibillion-dollar drugs. The drug group, which treats type 2 diabetes, could be linked to pancreatitis, a very serious inflammation of the pancreas that can lead to pancreatic cancer. David tells investors how several companies, such as Merck (NYSE:MRK), Bristol-Myers Squibb (NYSE:BMY) and AstraZeneca (NYSE:AZN) could be affected if the link is confirmed, and how serious the damage could be financially.