In diabetes, GEF, T cell lymphoma invasion and metastasis (Tiam1), is shown to be critical in orchestrating Rac1 activation; activation of Tiam1-Rac1-Nox2 signaling axis, an early event in the pathogenesis of diabetes, leads to mitochondrial damage and accelerated capillary cell apoptosis. The gene discussed is RAC1; the disease is diabetes mellitus.