Analysis Indicates Inhaled Insulin Safe Alternative to Injection

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Meta-analysis: efficacy and safety of inhaled insulin therapy in adults with diabetes mellitus, by L. Ceglia and colleagues. Ann Intern Med 145:665-675, 2006.

What is the problem and what is known about it so far?

Insulin helps control high blood glucose levels, but many people are reluctant to start insulin therapy because of the need for injections. A new form of insulin that can be inhaled has been on the market for about a year. Although the Food and Drug Administration has approved inhaled insulin, little is known about the long-term safety and effectiveness of drugs that are inhaled.

Why did the researchers do this particular study?

The researchers wanted to examine a number of studies of inhaled insulin in order to get a more complete and reliable picture of the safety and effectiveness of inhaled insulin.

Who was studied?

 The studies included 4,023 adults who had type 1 or type 2 diabetes.

How was the study done?

The medical literature and other databases were searched to find all randomized clinical studies of inhaled insulin that lasted at least 12 weeks. Sixteen studies were found. Two reviewers examined each study.

What did the researchers find?

Injectable insulin reduced A1C (a long-term measure of blood glucose control) slightly better than inhaled insulin, but equal numbers of people on the inhaled and injectable formulations reached the A1C level of 7% recommended by the American Diabetes Association. People who inhaled insulin were more likely to have low blood glucose levels than those taking oral diabetes medication, but about the same as those who took injectable insulin. In general, people preferred inhaled insulin to injectable insulin.

What were the limitations of the study?

The 12-week follow-up period may not be long enough to assess long-term safety of inhaled insulin. There could be subtle differences in the studies included in this project that affect the outcomes.

What are the implications of the study?

Inhaled insulin is a safe and effective alternative to injectable insulin for many people with diabetes. Longer-term studies are needed to see whether inhaled insulin remains safe if taken over a period of years.