The TSC1-TSC2 tumor suppressor complex serves as an interface between insulin and nutrient signaling pathways and the cell growth machinery. Recent work has indicated that the TSC1-TSC2 complex plays a role in the pathobiology of a number of tumor predisposition syndromes, including tuberous sclerosis (TSC1/2), Peutz-Jeghers syndrome (LKB1), and Cowden's syndrome (PTEN), in which the TSC/Rheb/mTOR axis is inappropriately active secondary to loss of tumor suppressor function. Recent work has demonstrated that TSC deficiency imposes a negative autoregulatory loop that suppresses insulin signaling at the post-receptor level, effectively resulting in cell autonomous insulin resistance. Exploitation of this insulin signaling deficiency may hold promise among tailored clinical therapies designed to manage tuberous sclerosis.