An improved mouse model for conditional and inducible genetic manipulation in preproglucagon-expressing cell lineages including pancreatic alpha-cells and enteroendocrine L-cells; a useful tool for performing temporally controlled genetic manipulation specifically in these cell types. Injection with tamoxifen induces CreERT2-mediated recombination at the Rosa-LSL-YFP locus with efficiencies of 88% and 95% for perinatal and adult alpha-cells, respectively. Previous models have only 50-70% recombination efficiency in alpha-cells.