Impact of Transition to Insulin U-500 during Pregnancy on Continuous Glucose Monitoring–Derived Glycemic Metrics among Women with Type 2 Diabetes

Insulin U-500 is a highly concentrated regular insulin that is five times stronger than standard U-100 and is used to treat severe insulin resistance. Glycemic data from continuous glucose monitoring (CGM) in relation to initiation of U-500 insulin in pregnancy with type 2 diabetes are limited. We examined CGM-derived glycemic measures before and after insulin U-500 transition during pregnancy among women with type 2 diabetes. We conducted a case-crossover study evaluating glycemic measures before and after transition to insulin U-500 during pregnancy among women with type 2 diabetes. The case period was from prenatal care to insulin U-500 transition, and the control period was after insulin U-500 transition to delivery. Outcomes included CGM metrics (time in range [TIR; 65–140 mg/dL], time above range [TAR], and time below range), mean glucose and standard deviation, estimated A1c per glucose management indicator, coefficient of variation, and number of hypoglycemic episodes and were compared pre versus post insulin U-500 transition. Adjusted linear mixed models were used. Among 21 women with type 2 diabetes, the median gestational age at prenatal care initiation was 11.1 weeks, at insulin U-500 transition was 25.4 weeks, and at delivery was 37.1 weeks. The insulin U-500 dose at initiation was 300 units/day and at delivery was 422.5 units/day. The TIR was higher, and TAR and mean glucose were lower post versus pre insulin U-500 transition (p < 0.05). In this cohort of pregnant women with type 2 diabetes, transition to insulin U-500 was associated with a modest improvement in some CGM-derived glycemic measures.