The weight loss caused by Byetta comes as a welcome for diabetics contrast to the weight gain, that often accompanies insulin and other diabetes medicines. The extra pounds can eventually worsen the disease. Some patients say Byetta has reversed the course of a disease that can lead to severe complications like amputations, blindness and kidney failure and even death.
Weight loss from Byetta could be a particularly important benefit for diabetics. Among the 21 million Americans with diabetes, about 90 percent have Type 2, which usually occurs in adulthood and has been linked to obesity and inactivity.
The drug seems so effective for weight loss that some nondiabetics have begun using Byetta as a diet drug — causing concern among doctors who say such use has not been medically tested and could be dangerous.
Byetta is not a cure-all, doctors caution. Some patients cannot tolerate its side effects. And it has never been studied as a weight-loss agent in people with normal blood sugar. Amylin Pharmaceuticals and Eli Lilly, which jointly make and market Byetta, say they strongly discourage its use solely as a diet drug. Based on tests in rats, moreover, some scientists have raised the possibility that Byetta may increase the risk of thyroid cancer, although no evidence of that link has appeared in human clinical trials.
Even without a big marketing push, prescriptions for Byetta are soaring, as news of the drug spreads among diabetics and doctors. From November to January, monthly prescriptions rose almost 40 percent, to almost 100,000, well ahead of analysts’ forecasts. Byetta costs about $170 a month, or $2,100 a year, slightly more than most other diabetes drugs, but most insurers cover it.