Two highly prevalent diseases, Type-2 diabetes mellitus and coronary heart disease (CHD), share risk factors. Excess levels of LDL-cholesterol have been overemphasized to uniformly encompass the development of CHD, and the origin of insulin resistance underlying Type-2 diabetes has not been fully elucidated. Autoimmune response has been recognized to be responsible only of a small minority of diabetes. The increasing trend in the worldwide prevalence of diabetes and the risk factors for both diseases are reviewed, the independent mediation for CHD of (central) adiposity in both diseases and the ‘hypertriglyceridemic waist’ phenotype are outlined. Evidence is described that serum lipoprotein (Lp)(a) concentrations, not only in excess, but also in apparently ‘reduced’ levels, as a result of autoimmune response, underlie both disorders and are closely related to insulin resistance.