Exubera is being presented as equally effective as injectable insulin, but more convenient. "By allowing insulin to be inhaled, Exubera could help dramatically reduce the insulin-initiation hurdles that result from fear of injections and therefore keep millions of patients from attaining appropriate control of their glucose levels," Pfizer says. The company says up to half of patients with type 2 diabetes who require insulin treatment decline it. Research shows that patients are three times more likely to follow a course of insulin treatment when an inhaled option is available, Pfizer says. But when the cost of inhaled insulin is added to the equation, skeptics say the convenience issue may be overstated. Another concern is how Exubera and other inhaled insulin products will affect the lungs. The American Diabetes Association notes that "you have to inhale a lot of insulin to get the amount your body needs. That's because only a small percentage of the inhaled insulin actually reaches the bloodstream and lowers blood glucose." The association adds that although short-term studies say inhaled insulin is safe, "the long-term safety remains a question." The advisory committee said people with lung disease shouldn't use Exubera. Pfizer says it will conduct a long-term study to assess Exubera's effect on lung function.