Dysregulated glucagon secretion accompanies islet inflammation in type 2 diabetes. We recently discovered that interleukin (IL)-6 stimulates glucagon secretion from human and rodent islets. IL-6 family cytokines require the glycoprotein 130 (gp130) receptor to signal. In this study, we elucidated the effects of a-cell gp130 receptor signaling on glycemic control in type 2 diabetes. IL-6 family cytokines were elevated in islets in rodent models of this disease. gp130 receptor activation increased STAT3 phosphorylation in primary a-cells and stimulated glucagon secretion. Pancreatic a-cell gp130 knockout (agp130KO) mice showed no differences in glycemic control, a-cell function, or a-cell mass. However, when subjected to streptozotocin plus high-fat diet to induce islet inflammation and pathophysiology modeling type 2 diabetes, agp130KO mice had reduced fasting glycemia, improved glucose tolerance, reduced fasting insulin, and improved a-cell function. Hyperinsulinemic-euglycemic clamps revealed no differences in insulin sensitivity. We conclude that in a setting of islet inflammation and pathophysiology modeling type 2 diabetes, activation of a-cell gp130 receptor signaling has deleterious effects on a-cell function, promoting hyperglycemia. Antagonism of a-cell gp130 receptor signaling may be useful for the treatment of type 2 diabetes.Islet inflammation (1,2) and pancreatic a-cell dysfunction (3-6) contribute to hyperglycemia in patients with type 2 diabetes. Pancreatic islets from patients with type 2 diabetes are infiltrated with macrophages (7,8), express elevated proinflammatory cytokines (9,10), and express features of fibrosis (11), consistent with reports from animals and primates with this disease (7,(12)(13)(14)(15)(16)(17)(18). The detrimental effects of inflammation on islet b-cell function were recently confirmed, when the interleukin (IL)-1 receptor antagonist reduced hyperglycemia and improved b-cell insulin secretion in patients with type 2 diabetes (1).Pancreatic a-cell dysfunction is detectable in the early stages of type 2 diabetes, where the inverse relationship between pulsatile insulin and glucagon secretion is lost (19). This dysregulation is associated with relative hyperglucagonemia, which contributes to the development of fasting hyperglycemia associated with frank type 2 diabetes (6). Indeed, inhibition of glucagon action by various means reduces hyperglycemia in rodent models of this disease (5,6).