Use of U-500 insulin in the treatment of severe insulin resistance

Background: Glycemic control is essential in the management of diabetes. However, many patients with diabetes are not achieving therapeutic targets, partly because they are receiving insufficient doses of insulin. This is particularly problematic in patients with severe insulin resistance, defined as insulin requirement >200 units/kg per day (>3 units/kg per day for pediatric patients). It is difficult to use U-100 forms of insulin at doses >200 units/kg per day because of the volume of insulin being administered subcutaneously. U-500, a concentrated form of insulin, may be useful in the treatment of these patients.Objective: Current practice regarding the use of U-500 insulin has been published elsewhere. This article presents an updated algorithm for the administration and dosing of U-500 insulin, based on clinical experience with severe forms of insulin resistance. Guidelines are provided for dose escalation of U-500 insulin.Methods: We reviewed the results of treatment with U-500 insulin in patients with severe insulin resistance. We analyzed the results, updated a pre-existing algorithm, provided additional practical information on the administration and dosing of U-500 insulin, and compared the cost of U-500 with that of U-100 insulin.Results: To date, we have treated 56 patients (age range, 9–54 years) with severe insulin resistance using U-500 insulin. Doses ranged from 1.5 to 566 units/kg per day. Based on the pharmacodynamic properties of U-500 insulin, this concentrated form must be administered and dosed differently than regular U-100 insulin. U-500 insulin cost more than U-100 insulin on a per-milliliter basis, but cost less in the end because of the lower volumes of insulin required and fewer syringes and pump cartridges needed to administer U-500 insulin.Conclusions: In our experience, U-500 insulin is a useful tool in the management of patients with severe insulin resistance. U-500 insulin alleviates the volume-related problems associated with U-100 insulin, making treatment with higher doses of insulin (≥200 units per day) more effective with U-500 insulin than with U-100 insulin.