Haffner SM, D'Agostino R, Mykkänen L, Hales CN, Savage PJ, Bergman RN, O'Leary D, Rewers M, Selby J, Tracy R, Saad MF. Proinsulin and insulin concentrations in relation to carotid wall thickness: Insulin Resistance Atherosclerosis Study. Stroke. 1998 Aug; 29(8):1498-503.