Pfizer said the company has 10 years of clinical studies on Exubera in adults and sees the drug as something that will reach patients earlier in the treatment of the disease, particularly those who don't like the idea of being injected with a needle and therefore avoid treatment.

It's the first new delivery mechanism for the treatment of adult patients with diabetes since the discovery of insulin in the 1920s.

Prior to the drug's approval, "patients with diabetes who need insulin to manage their disease had only one way to treat their condition," said Dr. Steven Galson, director of the FDA's Center for Drug Evaluation and Research. "It is our hope that the availability of inhaled insulin will offer patients more options to better control their blood sugars."

Caution Advised

However, the agency and doctors say not everyone will be able to use the new drug, particularly smokers and people with breathing problems such as asthma.

The drug's maker, Pfizer Inc. of New York, said the product could be available by midyear. The company's officials would not disclose a price for the product but Wall Street analysts forecast blockbuster sales that could reach $2 billion annually within five years.

A second inhaled insulin could be approved by the FDA next year so consumers are certain to hear more about the new treatment options.

With some 21 million people with diabetes in the United States alone and more than 5 million of them who take insulin injections, the product could be more convenient and potentially work more quickly than an injection in patients, studies and the FDA said. Doctors, though, cautioned that the drug does not have the history of safety and efficacy of injections and consumers should proceed cautiously.

Not for Everyone

Diabetes is a disease that affects the amount of insulin and sugar in a person's body. The FDA said Exubera is a human form of insulin and works by lowering blood sugar amounts. Through an inhaler, Exubera, a powdered form of insulin, is inhaled into the lungs.

There are two major types of diabetes -- type 1 and type 2. People with type 1 diabetes produce virtually no insulin and are dependent on insulin and could benefit from the inhaled Exubera. With type 2, the most common form of the disease, the body does not produce enough insulin or effectively use insulin, doctors say.

Type 2 diabetics could also benefit from Exubera but the FDA and doctors say Type 2 diabetics have many more options than insulin including pills and, when they are first diagnosed, can be put on treatment plans that include diet, exercise or other remedies.

The FDA did not know exactly how many of the estimated Americans who have either type 1 or type 2 diabetes would be candidates for an inhaled drug.

"It will not replace insulin in everybody," said Dr. Robert Meyer, director of the FDA's Office of Drug Evaluation who oversees metabolic and endocrine drugs. "It may not replace all of their injections."

Long-Term Safety Concerns

In fact, Pfizer's application to the FDA for Exubera was delayed for additional safety testing because of concern the product might cause lung damage.

To address such concerns, the FDA said Exubera should not be used by smokers or people who have quit smoking in the last six months. The agency also said Exubera is not recommended for patients with illnesses such as bronchitis or emphysema.

Smokers, in particular, were shown in studies to absorb too much of the drug and there was the potential for an overdose, Meyer said.

Some doctors may also shy away from using Exubera because it lacks the long-term safety data of injected insulin.

"Insulin injections have been safe and effective since the 1920s," said Dr. Marc Sandberg, a medical director at the Diabetes Health Center at Hunterdon Medical Center in Flemington, NJ, who said he was involved in an early clinical trial of inhaled insulin. "There are some reservations about inhaled insulins. We do not have the long-term safety data for inhaled patients."

May Help People Who Fear Injections

Exubera is not yet approved for children due to a lack of data. The FDA said it asked Pfizer to hold off on extensive studies in children until the safety in adults has been "well studied and assessed," an agency spokeswoman said.

Pfizer said the company has 10 years of clinical studies on Exubera in adults and sees the drug as something that will reach patients earlier in the treatment of the disease, particularly those who don't like the idea of being injected with a needle and therefore avoid treatment.

Pfizer said trials in children will be done later.

Avoiding any kind of treatment of diabetes can be dangerous. People who do not control their blood sugar levels can end up with serious health problems that include heart disease, kidney failure and blindness.

"Many people who could benefit from insulin are fearful of injections, so they delay treatment five years or 10 years, placing them at risk for serious complications," said Dr. William Cefalu, a Pfizer consultant and professor of medicine at Louisiana State University. "Now, for the first time patients can improve blood sugar control with fewer or no painful injections."