An inhaled form of insulin has been able to control blood sugar levels in diabetics for two years without harming their lung functions, researchers said on Sunday.
　　"The inhaled insulin continues to work. It continues to maintain glycemic control, at least up to the two-year point we have studied," lead researcher Dr. William Cefalu of the University of Vermont College of Medicine in Burlington told Reuters.

Results from a two-year follow-up study of 140 patients who participated in one of three earlier mid-stage clinical trials of the inhaled insulin were presented in San Francisco at a meeting of the American Thoracic Society.

The patients were treated with Exubera, a dry powder form of insulin being developed by Pfizer Inc., the largest US drug maker, and Franco-German drug company Aventis SA. The insulin is absorbed into the body through an aerosol made by Inhale Therapeutic Systems Inc..

The delivery of insulin deep into the lungs may eventually allow some people with Type 1 diabetes to cut back on injecting themselves with insulin, while some people with Type 2 diabetes who take oral drugs to control their diabetes may be able to eliminate injections, Cefalu said.

There are two types of diabetes -- a disease in which the body does not produce or properly use insulin, a hormone that is needed to convert sugar, starches and other food into energy. In people with Type 1 diabetes, which accounts for 5-10 percent of all cases and most often occurs in children and young adults, the body does not produce any insulin and it must be injected daily for them to stay alive.

In Type 2 diabetes, which accounts for 90-95 percent of cases, the body does not make enough, or properly use, insulin. People with type 2 diabetes usually develop the disease after age 45 and they need diabetes pills or insulin shots to help their bodies use sugar, or glucose, for energy.

This 24-month trial of Exubera, sponsored by Pfizer, looked at the patients' blood sugar levels, and found the treatment initially controlled the levels, and maintained them over the two-year period.

The study also examined patients' lung function, and found it was not adversely affected during the course of the study.

"The side effects appear to be comparable to the control group," Cefalu said, noting that hypoglycemia, or low blood sugar, is the most common side effect of both injected and inhaled insulin.

But only 10-15 percent of the insulin delivered through an inhaler is absorbed into the bloodstream, giving rise to the question of where the excess insulin goes and whether it could harm the patient.

Last week, Aventis told analysts that one of the 1,000 patients so far treated with Exubera had developed pulmonary fibrosis, a potentially fatal condition in which the lungs develop scar tissue. Analysts said the event mirrored the incidence of the condition in the general population.

"We did not see anything like that at my site," Cefalu said.

He said there is still no explanation for where the excess inhaled insulin goes. "There may be some loss to the device, some loss to the upper airway or it could be broken down," the researcher added.

For diabetics, keeping blood glucose levels as close to normal as possible can prevent or slow the progress of many complications of diabetes, providing extra years of healthy, active life.

Cefalu said it has been previously observed that both patients with Type 1 and Type 2 diabetes have preferred inhaled insulin over injections.

"In addition, patients with Type 2 diabetes may be reluctant to start insulin therapy even though two or more of the oral therapies may not be controlling the blood sugar levels. If inhaled insulin provides an acceptable alternative, patients may be started on insulin sooner, resulting in improved glucose control over time and reduced complications such as eye, kidney, or nerve disease," Cefalu said.

Pfizer, which plans to file by the end of this year for US Food and Drug Administration approval of Exubera, has said it will release results from a pivotal-stage trial of the inhaled insulin at next month's meeting of the American Diabetes Association

　　From ChinaDaily