956-P: Successful Use of U-500 Insulin with the Tandem X2 Pump with Control IQ (CIQ)

Objectives: The American Diabetes Association recommends the use of U-500 insulin for individuals with insulin dose requirements over 200 units per day. Commercially available insulin pumps are FDA-approved for U-100 insulin. Patients requiring high daily insulin doses must frequently refill pump reservoirs due to the use of large insulin volumes. U-500 allows for less frequent reservoir refills and a reduction in insulin infusion site discomfort. Previously, the VIVID study demonstrated the safety and efficacy of U-500 insulin with pump therapy used in manual mode. We describe a case of using U-500 insulin in a Tandem X2 insulin pump with the CIQ algorithm.

Methods: We reviewed clinical and insulin pump data for a patient before and after switching to U-500 Lispro insulin in a Tandem pump with the CIQ algorithm. The starting insulin dose was calculated as 20% of the U-100 insulin Total Daily Dose (TDD), with 50% allocated to basal insulin delivery. The carbohydrate ratio and correction factor were adjusted proportionally.

Results: Prior to switching to U-500 insulin, the patient's average TDD of insulin was 254.25 units, with a Time in Range (TIR) of 20%. A month following the transition, there was a marked improvement in TIR to 53% with a TDD of 40.53 units of U-500 insulin, without increasing the rate of hypoglycemia. Time spent in the CIQ algorithm averaged 94% per day. The mean blood glucose levels decreased from 250 mg/dL to 185 mg/dL. Additionally, the use of U-500 insulin extended the infusion set wear time from one day to three days.

Conclusion: This is the first-ever reported case highlighting the successful use of the CIQ algorithm with U-500 insulin in a Tandem X2 pump for a patient with a high insulin dose demand. Through appropriate dose conversions and pump setting adjustments, there was a marked improvement in glycemic control in a safe and effective manner. It provides a viable option for patients with severe insulin resistance to use automated insulin delivery systems.