Oral insulin fails to delay type 1 diabetes in high-risk population
medwireNews: Giving daily oral insulin to high-risk relatives of patients with type 1 diabetes did not delay the onset of the condition in the Type 1 Diabetes TrialNet Oral Insulin Study, although the investigators say that doubts surrounding the dose of insulin used means the case is not yet closed.
As reported in JAMA, Jeffrey Krischer (University of South Florida College of Medicine, Tampa, USA) and colleagues gave the study participants oral insulin at a daily dose of 7.5 mg, or placebo, for a median of 2.7 years.
However, this dose is considerably lower than the highest dose used in the Pre-POINT study, of 67.5 mg/day, which was also the only dose to elicit a larger immunomodulatory response than placebo. For this reason, the TrialNet researchers are now testing a range of oral insulin doses in relatives positive for microinsulin autoantibodies.
The researchers were aiming to reproduce the findings of a subgroup analysis of the DPT-1 study, in which participants with the highest autoantibody levels appeared to derive benefit from oral insulin, although the overall cohort did not.
To this end, they enrolled 560 autoantibody-positive participants, aged a median of 8.2 years, who had a relative (first, second, or third degree) with type 1 diabetes. The primary outcome was the onset of diabetes in the 389 of these participants whose first-phase insulin release on an intravenous glucose tolerance test was higher than either 60 or 100 μU/mL depending on their age and relationship to the type 1 diabetes patients.
During follow-up, 31% of this highest-risk group developed diabetes, but the annualized rate was not significantly different between those taking oral insulin and placebo, at 8.8% and 10.2%, respectively. The corresponding rates in the whole cohort were 8.7% and 10.4%, which again was not a significant difference.
Krischer and team note that use of immunomodulatory therapies in patients with newly diagnosed diabetes has met with some success in terms of preserving beta cell function.
“However, an effect at earlier stages of the disease in delaying onset of clinical diagnosis of diabetes would have a much more profound effect in relieving the burden of disease,” they observe.
“Despite marked advances in insulin delivery and glucose monitoring, there are still significant unmet needs for disease modifying therapy in type 1 diabetes.”
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