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Item #5 

Inhaled Insulin Not As Effective for Asthmatics

More insulin required for asthmatics to achieve glycemic control

Results of a study using an experimental aerosol insulin device suggest that diabetic patients with asthma may need to inhale more insulin to achieve similar glycemic control as their nonasthmatic counterparts.

The device, called the AERx insulin Diabetes Management System (AERx iDMS; Aradigm, Hayward, Calif.), is designed to deliver a controlled aerosol of liquid human insulin to the deep lungs for systemic absorption.

To see if airflow obstruction and other pathophysiological changes in patients with asthma alter distribution and absorption of inhaled insulin, Dr. Robert R. Henry of the VA San Diego Healthcare System in California and colleagues enrolled 17 asthmatic and 28 nonasthmatic diabetics in a two-part, open-label trial. Patients were excluded for a number of reasons, including treatment with oral, intravenous, intra-articular, or intra-muscular corticosteroids within 12 weeks or inhaled corticosteroids within 4 weeks.

In part one of the study, researchers assessed insulin pharmacokinetics and pharmacodynamics by having subjects inhale a single 1.57 mg (45 IU) dose of insulin on each of 2 dosing days. In part two of the study, they assessed the impact, if any, of inhaled insulin on pulmonary function by having subjects inhale a larger dose of insulin (4.7 mg [135 IU]).

Compared with nonasthmatics, asthmatic subjects absorbed significantly less inhaled insulin and, as a result, had less reduction in their blood glucose.

Inhaled insulin had no impact on pulmonary function. Results showed no worsening of the patients' hyper-reactivity airway state, wlth, with no clinically meaningful changes in FEV1, FVC, and FEV1/FVC values.

"Many patients with diabetes are reluctant to initiate insulin therapy because of needle anxiety," Dr. Henry said. "The availability of a noninvasive insulin delivery system such as the AERx iDMS will likely result in the earlier institution of insulin therapy and improved patient compliance, both of which could have multiple beneficial effects in the short and long run."  Diabetes Care 2003;26:764-769.

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