Is Oral Insulin Effective for Delaying Type 1 Diabetes Development?

The use of oral insulin did not delay the development of diabetes in autoantibody-positive relatives of patients with type 1 diabetes, according to a recent study.

For their randomized controlled trial, the researchers enrolled 560 participants who were relatives of patients with type 1 diabetes and had a least 2 autoantibodies, including insulin autoantibodies, and normal glucose tolerance (mean age 8.2 years). The main study group included 389 participants who had first-phase insulin release on an intravenous glucose tolerance test that was higher than the threshold. Secondary stratum 1 included 55 patients with an identical antibody profile as those in the main study group but a first-phase insulin release below the threshold. A total of 114 participants and 3 participants with different autoantibody profiles and first-phase insulin release combinations were included in secondary stratum 2 and 3 analyses, respectively.
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A total of 283 participants, including 203 from the main study group, received 7.5 mg of oral insulin per day and 277 participants, including 186 from the main study group, received placebo. The time to diabetes onset in the main study group was assessed as the primary outcome.

Overall, the HR for diabetes onset was 0.83 for the entire cohort of 560 participants.

Over the median 2.7 years of follow-up, 58 participants (28.5%) who received oral insulin and 62 participants (33%) who received placebo in the main study group were diagnosed with diabetes. The time to diabetes onset was not significantly different between the 2 groups, with a hazard ratio (HR) of 0.87.

Among those in secondary stratum 1, 13 participants (48.1%) who received oral insulin and 19 (70.3%) who received placebo were diagnosed with diabetes (HR 0.45). However, those who received oral insulin experienced a significantly longer time to diabetes onset.

Additionally, the HR for time to diabetes onset was 1.03 for participants in the other secondary stratum.

While no significant study-related adverse events were observed, 254 participants experienced infections, with 134 events occurring in the oral insulin group and 120 in the placebo group.

“Among autoantibody-positive relatives of patients with type 1 diabetes, oral insulin at a dose of 7.5 mg/d, compared with placebo, did not delay or prevent the development of type 1 diabetes over 2.7 years. These findings do not support oral insulin as used in this study for diabetes prevention.

—Melissa Weiss

Reference:

Writing Committee for the Type 1 Diabetes TrialNet Oral Insulin Study Group. Effect of oral insulin on prevention of diabetes in relatives of patients with Type 1 diabetes: a randomized clinical trial. JAMA. 2017;318(19):1891–1902. doi:10.1001/jama.2017.17070.