Abstract: The present invention provides novel methods of treatment of diabetes mellitus as well as methods of diagnosing the susceptibility of hypoglycaemia in an individual. The method of treatment includes administering to an individual a sufficient amount of at least one inhibitor of the renin-angiotensin II system and at least one antidiabetic, for example insulin. Another objective of the present invention is to provide methods of preventing hypoglycaemia in an individual in need thereof comprising administering to said individual a pharmaceutical effective amount of an inhibitor of the renin-angiotensin II system. In particular, such an individual may be an individual suffering from diabetes mellitus.