1. A use of an insulin sensitiser an insulin secretagogue and a biguanide antihyperglycaemic agent as a pharmaceutically acceptable carrier therefor for use as an active therapeutic substance for treating diabetes mellitus and conditions associated with diabetes mellitus wherein the insulin sensitiser is 5-[4-[2-(N-methyl-N-(2-pyridyl)amino)ethoxy]benzyl]thiazolidine-2.4-dione (Compound I) which comprises the administration of 2 to 12 mg of said Compound. 2. The use according to claim 1 wherein ...