Islet macrophages reside in the perivascular space next to islet blood vessels. They are long-lived and self-renewing, maintaining about two to ten macrophages per islet [1]. However, more than three decades after the first description of islet macrophages [2], our knowledge regarding the biological role of these cells is limited (reviewed in [3]). Emerging evidence indicates that islet macrophages are important for islet homeostasis and secrete numerous factors that modulate beta cell activity. Reciprocally, in this issue of Diabetologia, Weitz et al demonstrate that a factor secreted by beta cells is sensed by islet macrophages [4], revealing the possibility of a physiological, two-way dialogue between islet macrophages and pancreatic beta cells.
