The present invention relates to the use of NAD(P)H oxidase inhibitors to increase cellular uptake of glucose and in the treatment and/or prevention of diseases caused by insulin resistance or diseases related thereto, such as type II diabetes. Specifically, the invention relates to a method for identifying an agent useful for the treatment or prophylaxis of a medical condition associated with elevated levels of blood glucose, the method comprising (i) contacting a candidate agent with a mammalian NAD(P)H oxidase or NAD(P)H oxidase complex; and (ii) determining whether said candidate agent inhibits the biological activities of the NAD(P)H oxidase or NAD(P)H oxidase complex.