Beyond Erythropoiesis: Emerging Metabolic Roles

Infiltration of inflammatory cells into adipose tissue causes insulin resistance in animal models and is associated with insulin resistance in humans (1,2). Among potential ther-apeutic approaches, the hormone erythropoietin (EPO) exerts anti-inflammatory effects in a variety of nonery-throid tissues (3), in which the receptor for EPO (EPO-R) is widely expressed (4). Various observations suggest a rela-tionship between EPO and diabetes. There is an increased prevalence of anemia with inadequate EPO response in diabetes (5), and treatment of anemia slows the progres-sion of microvascular and macrovascular complications (6). EPO reduced glucose levels in nondiabetic humans (7) and reduced diet-induced obesity and suppressed glu-coneogenesis in rodents (8,9). While EPO increases adi-pose tissue oxidative metabolism and deletion of EPO i