NPY and type 2 diabetes mellitus: In this work, we combined histochemical and electrophysiological tools to investigate effects of FGF1 on NPY/AgRP neuron function both in WT mice and in NPY/AgRP-reporter mice that were crossed onto the Lepob/ob mouse background, enabling us to identify and target NPY/AgRP neurons for electrophysiological recordings in a highly FGF1-responsive mouse model of T2D.