The NOD mouse is a type 1 diabetes model that develops insulitis at 4-8 weeks of age, with frank diabetes occurring from 30 weeks of age . However, identifying beta cells during disease trajectory is challenging, since the polygenic NOD genetic background cannot easily be recombined with common inbred beta cell reporter strains (e.g. Ins1Cre;R26YFP). We and others have previously shown that GLP1R expression is beta cell specific and we thus hypothesized that LUXendins might open up the possibility to identify beta cells in NOD (and other polygenic) mice.