Dr Mauvais-Jarvis is a clinical endocrinologist who has contributed to our understanding of the pathophysiology of diabetes by characterizing ketosis-prone diabetic syndromes with gender dimorphism. Taking this clinical observation to the bench and using knockout mouse models, Dr Mauvais-Jarvis has revealed a novel paradigm on the role of the main female hormone estradiol and estrogen receptors in pancreatic beta-cell survival. Dr Mauvais-Jarvis and co-workers demonstrated that estrogen receptors favor survival via rapid extra-nuclear actions and identified the G-protein coupled estrogen receptor as a new player in islet survival. Recently, the Mauvais-Jarvis laboratory has also been working on estrogen and androgen receptor actions on insulin synthesis, islet lipid homeostasis and islet revascularization following transplantation. These studies have implications to improve human islet survival for transplantation in type 1 diabetes. Energy homeostasis is an integrated system designed to prevent negative energy balance that is regulated differently in both sexes. Another focus of the Mauvais-Jarvis laboratory is to understand how estrogen and androgen receptors program and regulate the sex differences in energy homeostasis.