Inhaled Insulin
Has No Adverse Effects Found After Two-Year Study
posted 05/28/03
Treatment with inhaled insulin (INH) is associated with an increase in insulin
antibodies, but continuing studies indicate that the insulin antibodies are not
associated with increased hemoglobin A1c (HA1c), increased need for insulin,
hypoglycemia, or allergic reactions.
These findings were presented during the 12th Annual Meeting & Clinical Congress of the American Association of Clinical Endocrinologists, May 14-18.
To access the impact of insulin antibodies (IABs) in patients completing initial safety studies, an uncontrolled extension study lasting up to 24 months was conducted using INH as the only form of short-acting insulin. Participants included 661 type 1 and 298 type 2 diabetic patients, previously treated with subcutaneous insulin, and 439 insulin naïve type 2 patients who had failed oral agent therapies.
A semi-quantitative radioligand-binding assay was performed to measure IABs at the beginning and end of the parent trial and every six months in the extension study. Binding levels present in normal human serum was subtracted from total binding results. Randomly selected samples reflecting a wide range of IAB levels were analysed from the subjects.
The results showed that INH-treated patients with either type 1 or type 2 diabetes experienced a rise in insulin antibody levels after being switched from short-acting SC insulin to INH.
"Our findings indicated that INH-associated IABs are predominantly of the IgG class, consistent with SC-associated IABs. No adverse clinical impact has been identified due to insulin antibody responses resulting from use of inhaled insulin," said lead author S. Edwin Fineberg, M.D., a professor of medicine at the University of Indiana School of Medicine, Indianapolis, United States. "The overall patterns of antibody responses are consistent with published SC insulin experience, he said.
Antibody levels in the INH-treatment arms were higher, relative to the control arms in which SC insulin regimens were maintained. Paediatric subjects with type 1 diabetes appeared to have higher baseline and end-of-study mean antibody levels compared to the pooled type 1 cohort (approximately 60% over 18 years of age). Patients with type 1 diabetes had higher baseline and end-of-study mean antibody levels (over 30% but under 35%, according to bar chart) than those with type 2 diabetes. The lowest levels of antibodies were detected in type 2 insulin-naïve patients who received INH in addition to oral antihyperglycemic agent therapy. The majority [92%] of those patients had insulin antibody percent binding levels that were less then 10%.
Data from the long-term extension trial shows that mean and median antibody levels peak at 12 to 18 months of exposure, continued Dr. Fineberg.
"The important thing to realize is that scatter plot and regression analyses suggest that insulin antibodies are not associated with increased HbA1c, short- or long-acting insulin doses, or hypoglycemia rates (overall or severe)," he said.
He and his colleagues pointed out that there were "no consistent associations" with fasting plasma glucose, or in the lung studies of forced expiratory volume during one second (FEV1) and carbon monoxide diffusing capacity tests. In addition, the pooled INH group did not have a higher incidence of allergic-type adverse events than the comparison groups, according to study data.
"Our conclusion is that treatment with INH is associated with an increase in insulin antibody levels," said Dr. Fineberg. "However, the analyses done so far suggest that insulin antibodies are not associated with increased HbA1c, insulin doses, hypoglycemia rates, or allergic reactions. This conclusion agrees with many other studies that also show no apparent connection between insulin antibodies and measurements of metabolic control or clinical safety."
[Study title: Inhaled Antibody Binding in Clinical Studies of Inhaled Insulin (Exubera™ ) in Patients with Type 1 or Type 2 Diabetes. Abstract 69]
Source: Diabetes In Control Dot Com.
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