Combination Use of U-500 Regular Insulin via Insulin Pump and Rapid-Acting U-100 Prandial Injections for Treatment of Pre-Existing Type 2 Diabetes in Pregnancy

The high-dose large-volume insulin injections that may become necessary during pregnancy due to marked pregnancy-induced insulin resistance may result in suboptimal therapeutic effectiveness. Use of U-500 insulin, a concentrated insulin formulation, has been suggested during pregnancy. However, the pharmacokinetic properties of U-500 insulin monotherapy can impede achievement of strict pregnancy glycemic targets. We propose a novel regimen for treatment of severe pregnancy-induced insulin resistance that enables precise delivery of U-500 basal insulin therapy through continuous subcutaneous insulin infusion (CSII) while maintaining the desired kinetics of prandial rapid-acting U-100 insulin therapy. This combination approach, guided by continuous glucose monitoring data, enabled achievement of pregnancy glycemic targets while reducing basal insulin requirements by approximately one-third. We report our method for (1) conversion to U-500 insulin delivery through CSII during pregnancy and (2) conversion from U-500 basal insulin delivery through CSII to U-100 intravenous insulin infusion therapy at delivery, to offer clinicians who encounter similar challenging scenarios a novel approach to diabetes management during pregnancy in the setting of marked insulin resistance.