There are no studies in the literature investigating the expression of proinflammatory(IFN-γ, TNF-α, IL-17A) and anti-inflammatory (IL-4, IL-10) cytokines in serum ofpatients with type 2 diabetes mellitus submitted to duodenojejunal bypass surgery withileal interposition without gastric resection. The gene discussed is IL4; the disease is type 2 diabetes mellitus.