The use of U-500 insulin in the management of highly insulin resistant diabetic patients is growing. There are a number of reports that have noted the effects of U-500 insulin using multiple daily injections or continuous subcutaneous insulin infusion on hemoglobin A(1c), weight, and total daily insulin dosage. The effect of U-500 insulin use on glycemic control, changes in body weight, total daily insulin dosage, incidence of hypoglycemia, and effect on lipid levels and blood pressure as well as patient satisfaction and quality of life will be reviewed. In addition, this article will delineate algorithms of U-500 use, compare multiple daily injections or continuous subcutaneous insulin infusion, and discuss U-500 insulin pharmacokinetics.