Oral insulin does not delay or prevent type 1 diabetes in autoantibody-positive, first- and second-degree non-diabetic relatives of type 1 diabetes patients, according to a study in JAMA.

Jeffrey P. Krischer, PhD, from the TrialNet Coordinating Center at the University of South Florida in Tampa, and associates conducted a series of trials in 87 locations across 9 countries to determine if oral insulin could help family members of patients with diabetes prevent or delay the development of type 1 diabetes. 

In this study, which ranged from March 2007 until January 2017 (final patient randomization took place December 2015), 560 of the 138,385 screened participants tested positive to one or more autoantibody, normally tolerated glucose, and were either a first-degree relative (ages 3 to 45) or a second/third-degree relative (ages 3 to 20). These participants were sorted by autoantibody test results into randomized oral insulin (7.5-mg fixed dose) or placebo groups and monitored every 6 months; 550 participants completed the trials.

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A total of 172 patients (31%) developed type 1 diabetes by trial termination. Although there were more individuals with diabetes in the placebo group, no significant evidence indicated any prevention with oral insulin (n=82 in the oral insulin group; n=91 in the placebo group). The rate of relatives developing diabetes was annualized at 8.7% (oral insulin) and 10.4% (placebo) with a hazard ratio of 0.83. The duration for development of diabetes between the two groups was insignificant with a median follow-up of 2.7 years.

The researchers noted many restrictions associated with this investigation and suggest future studies to take more variables into account. 

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“This study has several limitations,” the authors stated. “This trial enrolled participants based on evidence of autoimmunity but did not take into account genetic background, age at onset, and type of first-appearing diabetes related autoantibody. The emerging literature now suggests that future trials need to consider these factors.”


  1. Krischer JP; 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 Nov 21. doi:10.1001/jama.2017.17070