Despite suggestive evidence from studies on experimental pathology and cell biology of the arterial wall and from clinical and epidemiological studies on non-diabetic subjects indicating that hyperinsulinaemia might be associated with an increased risk of atherosclerotic vascular disease (ASVD) information concerning the role of hyperinsulinaemia as a risk factor of ASVD in diabetic patients still is circumstantial. A few cross-sectional and still fewer prospective studies in patients with non-insulin-dependent diabetes (NIDDM), including two ongoing studies carried out by our own research group, have shown associations between hyperinsulinaemia and the occurrence of ASVD, but these data still are far from consistent and conclusive. Further studies applying combined clinical and epidemiological approach, building upon the results of experimental research concerning possible mechanisms, are needed for better clarification of the role of hyperinsulinaemia as a risk factor of ASVD in NIDDM.