The minimum model modified by the administration of insulin provides an objective and relatively easily measured index of peripheral sensitivity to insulin which was significantly lower (p <0.02) in familial combined hyperlipidemia (FCH) with ischemic heart disease (IHD) than in FCH without IHD and in control subjects (1.2 +/- 0.6, 1.9 +/- 1.0, 2.9 +/- 1.2 x 10(-4) mU/L/ min, respectively). In patients with FCH, insulin resistance explains, at least in part, their metabolic alterations (hypertension, abnormal glucose tolerance, hyperinsulinemia) and elevated IHD.