High-dose insulin therapy: is it time for U-500 insulin?

OBJECTIVE: To provide an overview of U-500 regular insulin action, review published clinical studies with U-500 regular insulin, and offer guidance to practicing endocrinologists for identifying patients for whom U-500 regular insulin may be appropriate.
METHODS: This review has been produced through a synthesis of relevant published literature compiled via a literature search (MEDLINE search of the English-language literature published between January 1969, and July 2008, related to U-500, insulin resistance, concentrated insulin, high-dose insulin, insulin pharmacokinetics, and diabetes management) and the authors' collective clinical experience.
RESULTS: The obesity epidemic is contributing to an increase in the prevalence of type 2 diabetes, as well as to increasing insulin requirements in insulin-treated patients. Many of these patients exhibit severe insulin resistance, manifested by daily insulin requirements of 200 units or greater or more than 2 units/kg. Delivering an appropriate insulin volume to these patients can be difficult and inconvenient and may be best accomplished with U-500 regular insulin by multiple daily injections or with continuous subcutaneous insulin infusion, rather than with standard U-100 insulin. Implementation of U-500 regular insulin in patients previously on other insulin formulations is described with a treatment algorithm covering dosage requirements ranging from 150 to more than 600 units per day on the basis of the authors' experience.
CONCLUSIONS: Regimen conversion of appropriately selected patients from high-dose, U-100 insulin to U-500 regular insulin therapy on the basis of the recommendations presented in this article may potentially result in improved glycemic control and lower cost.