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Oral insulin pill ineffective for delaying, preventing type 1 diabetes progression

Carla J. Greenbaum



The risk for type 1 diabetes development was not decreased in autoantibody-positive relatives of patients with type 1 diabetes randomly assigned to oral insulin, and oral insulin did not delay the time to diabetes progression, study data show.

“We now know that we can identify people long before they have clinical type 1 diabetes,” Carla J. Greenbaum, MD, chair of Diabetes TrialNet and director of the diabetes program at Benaroya Research Institute in Seattle, told Endocrine Today. “Indeed, we now consider that having two or more islet autoantibodies (immune markers in the blood) is an early stage of type 1 diabetes. TrialNet’s aim is to find therapies that can delay or prevent disease progression from early stages to clinically apparent disease.”

Greenbaum and colleagues evaluated data from 560 relatives of patients with type 1 diabetes randomly assigned to daily 7.5 mg oral insulin or placebo; participants underwent an oral glucose tolerance test every 6 months. Participants were enrolled between March 2, 2007, and Dec. 21, 2015, and followed until Dec. 31, 2016.

“We know that family members have a 15 times increased risk of developing type 1 diabetes. ... Thus, an important clinical implication about this study is that family members should be told about their increased risk and be offered the opportunity to be tested for antibodies in a research study,” Greenbaum said.

Researchers stratified participants by antibody type: The main study group included participants positive for islet cell antibodies or insulinoma antigen 2 and glutamic acid decarboxylase antibodies, and insulin release on IV glucose tolerance test higher than the threshold (n = 389); secondary stratum one included participants with an identical antibody profile as the main study group but insulin release lower than the threshold (n = 55); secondary strata two (n = 114) and three (n = 3) included participants with different antibody profiles and first-phase insulin release threshold combinations.

Overall, 31% of all participants were diagnosed with type 1 diabetes, as were 31% in the main study group.

The annualized rate of diabetes did not significantly differ in the main study group between participants assigned to the oral insulin pill (8.8%) or placebo (10.2%).

The annualized rate of diabetes was lower in the oral insulin pill group in the secondary stratum compared with the placebo group. Similarly, the median time to diabetes was longer in the oral insulin group (55.3 months) compared with the placebo group (24.3 months) for a difference of 31 months.

The annualized rates of diabetes for secondary strata two and three were not significantly different between the oral insulin pill and placebo groups.

No serious adverse events or episodes of severe hypoglycemia were reported.

“While the overall study results were negative (no effect of treatment to delay or prevent the disease), the study results highlight that type 1 diabetes is a heterogenous disease (ie, with different causation in different people) and that oral insulin may be helpful in only a subset of people,” Greenbaum said. “It is also possible that oral insulin is more helpful at a certain point in time, such as when beta cell function starts to decline prior to the onset of disease. Future research studies will focus on understanding causes of heterogeneity in type 1 diabetes progression and response to therapy.” – by Amber Cox

For more information:

Carla J. Greenbaum, MD, can be reached at cjgreen@benaroyaresearch.org.

Disclosures: Greenbaum reports she has served as an advisor for Eli Lilly. Please see the study for all other authors’ relevant financial disclosures.