Human proIslet Peptides (HIP) and HIP analogs and derivatives thereof, derived from or homologous in sequence to the human REG3A protein, chromosome 2p12, are able to induce islet neogenesis from endogenous pancreatic progenitor cells. Human proIslet Peptides are used either alone or in combination with other pharmaceuticals in the treatment of type 1 and type 2 diabetes and other pathologies related to aberrant glucose, carbohydrate, and/or lipid metabolism, insulin resistance, overweight, obesity, polycystic ovarian syndrome, eating disorders and the metabolic syndrome.