In 2011, we and others made an unexpected discovery: In rodent models of uncontrolled type 1 diabetes (T1D), the most severe manifestations of insulin deficiency — hyperglycemia and diabetic ketoacidosis (DKA) — can be fully reversed by infusing the adipocyte hormone leptin directly into the brain (1, 2). The gene discussed is LEP; the disease is Hyperglycemia.