Leptin-Insulin Interrelationships

The relationship of leptin to insulin is complex and our understanding of the interaction is evolving. Leptin is secreted from white adipocytes and levels correlate with adipose tissue mass. Via hypothalamic leptin receptors (ObR), it restricts food intake and increases energy expenditure in normal individuals. Leptin is implicated in decreased production and secretion of insulin by the pancreatic beta (β) cell. Insulin, conversely, stimulates leptin secretion in an adipocyte-insulin feedback loop. The studies available to date, however, have had varying results as to whether leptin is an antidiabetogenic protein. This chapter will delineate the relationships on leptin secretion and action.