Introduction: Glucagon is the only approved medicine for severe hypoglycemia available for caregivers of people with diabetes. Nasal glucagon (NG) was recently approved in the USA as a needle-free, ready-to-use alternative to injectable glucagon. This simulated user experience study in Japan compared NG and intramuscular glucagon (IMG) administration by caregivers, and NG administration by untrained third parties. Methods: This was an open-label, single-center, partially randomized crossover, simulated user experience trial conducted in Japan (October 2018 to December 2018). Caregivers who live with and care for a relative with diabetes were randomized (1:1, stratified by patient diabetes type 1 or 2) to one of two simulated administration sequences (group 1: NG then IMG; group 2: IMG then NG). Caregivers received training on each device 2 weeks before simulated administration of the device. Third parties received no training and only conducted simulated NG administration. Outcome measures included the percentage of successful administrations (based on critical step completion and dose; primary outcome), time to complete administration, and user satisfaction/ preferences. Results: In caregivers (N = 19), the percentage of successful administrations was greater (89.5% vs 26.3%, P \ 0.001) and mean time to complete administration was shorter (23.9 vs 207.3 s, P \ 0.001) with NG than with IMG. In third parties (N = 20), 95% of NG administration attempts were successful (mean time to complete administration, 55.5 s). All caregivers and 80% of third parties reported that the NG device was easy to use. All caregivers and 70% of Enhanced Digital Features To view enhanced digital features for this article go to https://doi.org/10.6084/ m9.figshare.9784958.