Approximately 10 percent of premature coronary artery disease (CAD) morbidity and mortality in the general population is due to insulin dependent diabetes mellitus (IDDM). By age 55, 35 percent of IDDM patents die of CAD, in contrast to only 8 percent of nondiabetic men and 4 percent of women. In the U.S., IDDM affects at least 750,000 persons and this number is growing rapidly as the effect of increasing incidence and improved survival. Tight blood glucose control can slow the development of microvascular complications but a protective effect on heart disease has not been convincingly demonstrated.