Researchers take first steps toward the Holy Grail of insulin inhalation
Two studies bring alternative to injections one step closer to reality
Researchers at the 58th Annual Scientific Sessions of the American Diabetes Association in Chicago gave diabetics an optimistic glimpse of a pain-free future when they released the results of two clinical studies investigating the use of insulin inhalers.
The two studies of 121 diabetics show that a new inhalation system is at least as effective as injected insulin for controlling the symptoms of Type I and Type II diabetes.
The goal: Reducing use of injections
"Getting away from insulin injections is one of the Holy Grails of diabetes," says Jay S. Skyler, MD, professor of medicine, pediatrics, and psychology at the University of Miami and author of one of the studies, Treatment of Type I Diabetes Mellitus With Inhaled Human Insulin: A 3-Month Multicenter Trial.
The studies investigated the effectiveness of a collapsible, flashlight-sized aerosol system, similar to an asthma inhaler, created by Inhale Therapeutics Systems in San Carlos, CA, and being developed for use in diabetes in collaboration with Pfizer Inc.
The inhaler delivers a dose of insulin in dry powder form through the mouth, directly to the lungs, where it enters the blood as a rapid-acting insulin. Patients take one or two spritzes before meals.
"Both groups achieved improvements in control, as would be expected by the closer monitoring and targeting used in clinical trials," says Skyler. "The notable achievement was that the inhaled insulin performed as well as the subcutaneous regimen when levels of HbA1C were examined."
Inhalation performed as well as injections
In one study, Skyler and colleagues in the Inhaled Insulin Phase II Study Group randomized 70 patients with Type I diabetes from 10 study sites to receive either inhaled treatment or subcutaneous injections for three months. Those in the inhaled insulin treatment group took one injection of slow-acting insulin at bedtime in addition to one or two inhalations of insulin prior to each meal.
Inhalation therapy appeared to perform as well as injected insulin. HbA1C levels averaged 8.5% at baseline and 7.8% after three months of therapy among patients who inhaled insulin. The subcutaneous group averaged 8.5% at baseline and 7.7% after three months.
In the second study, Treatment of Type II Diabetes Mellitus With Inhaled Human Insulin: A 3-Month Multicenter Trial, William T. Cefalu, MD, of the University of Vermont, Burlington, and associates at the same 10 clinical sites focused on patients with Type II diabetes. They randomized 51 subjects to either inhaled insulin or injected insulin. Both groups experienced a drop of 0.72% in HbA1C levels from baseline after three months.
Researchers have studied alternative methods of insulin for years. Oral methods, such as pill form, don't work because digestive acids in the stomach destroy insulin. Nasal spray methods were examined, but there was difficulty in controlling the dosage and they tended not to work in patients with colds.
Cefalu calls the lungs an ideal point of entry for insulin because the surface area in the lungs is huge, thanks to an abundance of alveoli. He also points out that giving inhaled insulin before meals throughout the day better mimics the natural action of the pancreas, compared to taking one long-acting insulin injection in the morning.
This treatment not for everyone
Despite the apparent success of the inhalers, researchers express doubts that they will work for everyone. "I suspect there is a group of patients, such as those with asthma, who will not be able to inhale insulin, just as there are contraindications with other types of medications," says Skyler. His study excluded smokers as well as those with compromised pulmonary capabilities.
While testing revealed no significant side effects or changes in pulmonary function, it did demonstrate a behavioral impact. More than 90% of the Type II participants and 80% of the Type I participants wanted to continue on the system for a year when offered a choice. Several clinical trials, some including children ages 12 and up, are expected to begin in November.
For more information on inhaled insulin, contact:
Jay S. Skyler, MD, Professor of Medicine, Pediatrics and Psychology, University of Miami. Telephone: (305) 243-6146.
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