Intranasal insulin appears safe and may stabilize beta-cell and immune function in individuals at risk for type 1 diabetes. Mucosal administration of insulin retards development of diabetes in the nonobese diabetic (NOD) mouse, a model of autoimmune type 1 diabetes, the authors explain, but such mucosa-mediated immune responses to potentially therapeutic self-antigens have not yet been documented in humans.
Dr. Leonard C. Harrison from The Walter and Eliza Hall Institute of Medical Research, Victoria, Australia and colleagues investigated the safety and immune effects of intranasal insulin in 38 individuals at risk for type 1 diabetes.
Six participants in each arm of the crossover study (intranasal insulin-first and placebo-first groups) developed diabetes a median of 1.1 years from entry, the authors report. Eleven of these participants had baseline first-phase insulin responses to intravenous glucose (a measure of beta-cell function) no higher than the first percentile.
Circulating insulin antibodies increased significantly during intranasal insulin treatment, the report indicates. Intranasal insulin was also associated with significant decreases in T-cell proliferation to insulin, the researchers note. "The changes in immunity to insulin conform to the pattern of Th1 to Th2 immune deviation that has been associated with mucosal tolerance and with protection from diabetes in the NOD mouse," the investigators explain.
"This is, to our knowledge, the first demonstration in humans of an effect of mucosally administered autoantigen on potential surrogate disease markers," the authors write. "Although these immune effects are consistent with the induction of mucosal tolerance and are in accord with the literature, they do not constitute proof of immune tolerance to insulin."
"The ultimate demonstration of this in humans would be the ability of intranasal insulin to prevent or delay diabetes onset," the researchers add. "We propose that the present study provides a rationale to determine in a formal trial whether intranasal insulin is immunotherapeutic and retards beta-cell destruction and progression to clinical diabetes." Diabetes Care 2004;27:2348-2355
WarmFeet Kit can help with painful neuropathy and wound healing.
To Find our more:
The 10,000 STEP STUDY:
"The Results". A simple answer to a difficult problem.