A recent study published in Molecular Psychiatry proposes a cellular mechanism that may contribute to decreased insulin production in individuals with type 2 diabetes mellitus (T2DM).1 Using a combination of cell culture experiments, animal models and studies in T2DM patients, the authors show that an up-regulation of tau in β-islet cells can inhibit pancreatic insulin secretion through changes in microtubule assembly.1 The gene discussed is MAPT; the disease is diabetes mellitus.