This comes just as its maker, Amylin Pharmaceuticals, was preparing to deliver a timed-release version to the market, a weekly pill to take the place of twice-daily injections.
The news puts those plans in doubt, since the drug's effect can't be "turned off" if a pancreatic problem develops.
A second new class of drug, protease dipeptidyl peptidase (DPP-IV), acts to increase the effectiveness of naturally-occurring GLP-1, but its safety and efficacy is not fully established, especially with long-term use.
Given the problems with GLP-1s, expect enormous reluctance to accept such results at face value. This is bad news for DPP-IV drugs like Januvia, which is taken as a daily pill.
But it's worse news for patients. Those with advanced diabetes have concerns about drugs they might take. Those with prediabetes face the fact there are few drugs for them at all. That number was estimated at 12 million in 2003.
The standard protocol for prediabetes thus remains weight loss and exercise. The oldest pill in the doctor's bag, metformin, is your only choice if you can't follow that advice.
Sorry, no miracles today.