Oral insulin does not alter gut microbiota composition of NOD mice

BackgroundOral insulin as a preventive strategy and/or treatment of type 1 diabetes has been the target of much research. Producing oral insulins is a complex and challenging task, with numerous pitfalls, due to physiological, physical, and biochemical barriers. Our aim was to determine the impact of oral insulin on the delicate gut microbiota composition. MethodsFemale nonobese diabetic mice were given oral porcine insulin 2 times a week from 5weeks of age for 4weeks, and then subsequently once a week for 21weeks, or until euthanized. The mice were divided into groups on a gluten-reduced diet or a standard diet. Gut microbiota composition was analysed based on faecal samples, and the type 1 diabetes incidence of the mice was monitored. ResultsWe observed no influence of the oral porcine insulin on the gut microbiota composition of mice on a gluten-reduced or a standard diet at 9weeks of age. Also, the administration of oral insulin did not influence the incidence of type 1 diabetes at 30weeks of age. ConclusionsOral porcine insulin does not alter the gut microbiota composition of nonobese diabetic mice on either a gluten-reduced diet or standard diet. Also, the oral porcine insulin did not influence the incidence of type 1 diabetes in the groups.