The topic of this book is prevention of type 2 diabetes mellitus and cardiovascular disease which are increasing by epidemic proportions all over the world. Metabolic syndrome is well established risk factor for type 2 diabetes mellitus and cardiovascular disease. Hyperinsulinaemia is considered as the earliest stage of development of type 2 diabetes and a core defect unifying the cardiovascular cluster of the metabolic syndrome. Treatment of the metabolic syndrome and hyperinsulinaemia is essential for the prevention of type 2 diabetes and cardiovascular disease. Metformin is a medication of first choice in therapeutic strategy of type 2 diabetes. The book comprises of two research articles representing results of metformin treatment in people at high risk for development of type 2 diabetes mellitus and cardiovascular disease such as those with hyperinsulinaemia, normal glucose tolerance and metabolic syndrome.