The first clinical trials using an inhaled form of insulin to treat diabetics have proved highly successful, paving the way for a greatly reduced reliance on painful and inconvenient injections of the life-saving hormone, scientists reported Tuesday.
The key to the study is the development of a finely powdered form of insulin that is sucked through the mouth into the lungs, where it is rapidly absorbed into the bloodstream to control blood sugar levels.
Studies involving 121 Type 1 and Type 2 diabetics showed that the inhaled insulin is at least as effective as injected insulin in controlling the symptoms of diabetes, has no side effects in the lungs, and is much more popular with patients, two teams of researchers told a Chicago meeting of the American Diabetes Assn.
"These studies present the first evidence that there are true alternative ways to administer insulin," said Dr. William T. Cefalu of the University of Vermont, who led one of the studies.
"This is absolutely a breakthrough in diabetes therapy," said Dr. Michael Bush of Beverly Hills, a past president of the California affiliate of the American Diabetes Assn. "That's an overused word, but this is truly a breakthrough."
Diabetes develops when the pancreas can no longer produce sufficient quantities of insulin, a hormone that regulates the metabolism and storage of sugars from food.
About 1 million Americans suffer from Type 1 diabetes, which usually develops in childhood and always requires insulin for control, and another 15 million suffer Type 2, which usually develops later in life and can occasionally require insulin injections.
The new system, developed by Inhaled Therapeutic Systems of San Carlos, could prove to be of great benefit to a large fraction of those with the disease.
It certainly was to Paul Matelis, a 50-year-old Florida accountant who has been taking insulin injections for 35 years and who participated in the clinical trials.
"I can't even begin to tell you how much I like this," he said Tuesday. "It has been giving me a lot more flexibility and control of my diabetes. And it's a lot more convenient. You don't have to keep the insulin refrigerated; you don't have to carry needles, alcohol swabs and other paraphernalia when you go on a trip. It gives me a lot more freedom."
The researchers will begin the final, phase 3 trials on 1,000 patients this fall. If those are successful, the product could be on the market within two years, they said.
Researchers have long sought a better way to deliver insulin. Swallowing a pill does not work, because the insulin is destroyed by acids in the stomach.
Studies of sniffing insulin through the nose were bogged down by dosing problems, irritation of the nasal passages and erratic absorption of the hormone--especially if the user had a cold.
The new system apparently avoids those problems. The flashlight-sized device allows the user to suck the dry powder through the mouth and directly into the lungs. The lungs have a surface area about the size of a tennis court, Cefalu said, and that allows the drug to be absorbed rapidly.
"All the patient has to do is breathe, and most patients know how to do that," said Dr. Jay S. Skyler of the University of Miami.
One team, headed by Skyler, studied 70 patients with Type 1 diabetes. Half of the subjects continued their prior regimen of two to three injections of insulin per day, while the other half took one or two inhalations of the powdered insulin before each meal and one injection of slow-acting insulin at bedtime.
Slow-acting insulin is like a timed-release drug that provides a constant, low level of insulin through the night. This type of insulin cannot now be administered by inhalation, so Type 1 recipients would still have to give themselves one injection at night.
After three months, the team found that blood sugar levels in the two groups were virtually identical. The researchers also performed extensive lung function studies and found no problems attributable to the insulin. The patients also did not suffer any unusual episodes of hypoglycemia (low blood sugar), as some critics had suspected that they might with inhalation.
"Basically, it works, and the patients tended to prefer it," Skyler said of the inhaled insulin. Some of them have now been using the system for more than a year with continued good results, he said.
The second study, headed by Cefalu, who is also at the Fletcher Allen Health Care hospital in Burlington, involved 51 patients with Type 2 diabetes. It can often be controlled by diet or with drugs that stimulate production of insulin by the body. But as patients age, they often begin to require insulin injections.
The study was performed in the same fashion as that with the Type 1 diabetics, with the exception that the patients did not receive a nighttime injection. The results were virtually identical, Cefalu said.
The phase 3 trial is expected to begin in November and to last for six months to one year. People interested in participating in the study can volunteer by calling 1-800-438-1985.
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No Needles Needed
Studies are showing that an inhaled form of insulin may be an alternative to injections for treating diabetics.
1. Patient inhales a fine powder form of insulin as an aerosolized cloud.
2. Insulin reaches deep lung tissue.
3. Insulin passes from deep lung into bloodstream, where it controls blood sugar levels.
\o7 Source: Inhale Therapeutic Systems\f7