Inhaled Insulin
Inhaled Insulin Can Help Control Type 2 Diabetes Mellitus
What is the problem and what is known about it so far?
Diabetes Mellitus is a condition in which the body loses control over blood glucose (sugar) levels because of lack of insulin (Type 1) or reduced effectiveness of insulin (Type 2). This loss in control results in high blood glucose (hyperglycemia) which damages blood vessels and can lead to nerve damage, blindness, kidney failure, heart and blood vessel disease. Type 2 diabetes can often be treated with pills (oral diabetes medication), but when the diabetes becomes more advanced, injections of insulin become necessary to control the blood glucose. Some people are unwilling to begin injecting themselves with insulin, so their blood glucose becomes uncontrolled. Recently, a powder form of insulin, which can be inhaled has been created and offers another option for diabetes control.
Why did the researchers do this particular study?
To determine if adding inhaled insulin to standard oral medication can bring uncontrolled type 2 diabetes under control.
Who was studied?
Participants were 68 patients, aged 35 to 65 years, with type 2 diabetes who were already being treated with oral diabetes medication but still had poorly controlled blood glucose levels as measured by glycosylated hemoglobin (HbA1c).
How was the study done?
For the 12 weeks of this study 36 patients received only their standard oral diabetes medication while 32 patients received their standard medication plus inhaled insulin 3 times a day before meals. Patients in the insulin group received individualized doses of inhaled insulin to achieve before and after meal targets. Patients in both groups were required to record their blood glucose levels several times a day. All patients had HbA1c measured before the study as well as at weeks 4, 8, and 12. The two groups' findings were compared.
What did the researchers find?
Over the course of the 12 week study, patients receiving only oral medications had no significant changes in HbA1c and blood glucose levels. Patients receiving both inhaled insulin and oral medications reduced both HbA1c and glucose levels by about 25 percent (one quarter). However, the patients who received inhaled insulin gained an average of 2.5 kg (5.5 pounds) more than did patients receiving only oral medications over the 12 weeks. Seven out of ten patients receiving inhaled insulin had at least one episode of low blood glucose (hypoglycemia) resulting in dizziness or weakness.
What were the limitations of the study?
This study followed a small number of people for a short period of time. Only patients without lung disorders participated. While no obvious changes in lung function were noted, the long-term effects of inhaled insulin on the lungs, the effects of inhaled insulin in people with asthma or other respiratory disease and other safety issues need further study.
What are the implications of the study?
Inhaled insulin may be an alternative to injected insulin for control of advanced type 2 diabetes. Limiting the rise in blood glucose after a meal helps overall blood glucose control.
Summarized by Wells Chandler, College of Medicine, University of Vermont.
Summarized from "Inhaled Insulin Provides Improved Glycemic Control in Patients With Type 2 Diabetes Mellitus Inadequately Controlled With Oral Agents: A Randomized Controlled Trial". Weiss, Stuart R. et al. The Archives of Internal Medicine, October 27, 2003, Volume 163, Pages 2277-2282.
