Abstract: A method of prevention or treatment of diabetic neuropathy and the other long term complications of diabetes mellitus including complications in the cardovascular system, kidneys and eyes wherein effective amounts of one or both of i) gamma-linolenic acid and/or one or more of the metabolites of gamma-linolenic acid (DGLA, AA, 22:4 n-6 or 22:5 n-6) and ii) 18:4 n-3 and/or one or more of the metabolites of 18:4 n-3 (20:4 n-3, 20:5 n-3, 22:5 n-3, 22:6 n-3) are administered against such complications as such or in the form of an ester, salt, amide or other derivative convertible in the body thereto, alone or in an acceptable pharmaceutical carrier or diluent.