review of the literature yields much evidence against a correlation between duration of non-insulin-dependent diabetes mellitus (Type 2 diabetes) and the degree of coronary atherosclerosis or the risk of clinically evident coronary heart disease (CHD). Furthermore, an increased risk of CHD, similar to that in previously diagnosed diabetic subjects, has been demonstrated in persons with impaired glucose tolerance. These observations suggest that an increased risk of CHD is not a consequence of the development of diabetes (i.e. persistent hyperglycaemia). It is more likely that diabetes develops in individuals who already possess characteristics which increase the risk of CHD in addition to the risk of developing diabetes.