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 (MRK 0.44%), Bristol-Myers Squibb (BMY 1.30%) and AstraZeneca (AZN 0.28%) could be affected if the link is confirmed, and how serious the damage could be financially.