Recent evidence suggests that IL-1beta-mediated glucotoxicity plays a critical role in type 2 diabetes mellitus. Although previous work has shown that inhibiting IL-1beta can lead to improvements in glucose control and beta-cell function, we hypothesized that more efficient targeting of IL-1beta with a novel monoclonal antibody, XOMA 052, would reveal an effect on additional parameters affecting metabolic disease. In the diet-induced obesity model, XOMA 052 was administered to mice fed either normal or high-fat diet (HFD) for up to 19 wk. XOMA 052 was administered as a prophylactic treatment or as a therapy. Mice were analyzed for glucose tolerance, insulin tolerance, insulin secretion, and lipid profile. In addition, the pancreata were analyzed for beta-cell apoptosis, proliferation, and beta-cell mass. Mice on HFD exhibited elevated glucose and glycated hemoglobin levels, impaired glucose tolerance and insulin secretion, and elevated lipid profile, which were prevented by XOMA 052. XOMA 052 also reduced beta-cell apoptosis and increased beta-cell proliferation. XOMA 052 maintained the HFD-induced compensatory increase in beta-cell mass, while also preventing the loss in beta-cell mass seen with extended HFD feeding. Analysis of fasting insulin and glucose levels suggests that XOMA 052 prevented HFD-induced insulin resistance. These studies provide new evidence that targeting IL-1beta in vivo could improve insulin sensitivity and lead to beta-cell sparing. This is in addition to previously reported benefits on glycemic control. Taken together, the data presented suggest that XOMA 052 could be effective for treating many aspects of type 2 diabetes mellitus.