Type1 diabetes mellitus (T1DM) results from auto- immune destruction of insulin-producing β cells and is characterized by the presence of insulitis and β-cell autoantibodies. Up to one third of patients develop an autoimmune polyglandular syndrome (APS). Presence of other autoimmune disorders in patients with T1DM has been associated with increased morbidity and mortality. Hypoglycemia resulting from concurrent hypothyroidism or adrenal crisis can be dangerous; starting replacement therapy for hypothyroidism may result in adrenal crisis if background hypocortisolism is not recognized. Early detection of antibodies and latent organ-specific dysfunction is advocated to alert physicians to take appropriate action in order to prevent full-blown disease.