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Case presentation
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A 46-year-old man with type 1 diabetes, obesity (BMI 33.3 kg/m²), severe insulin resistance, and impaired hypoglycemia awareness (Gold score 6) experienced recurrent hypoglycemia, particularly during overnight work shifts. He had previously transitioned from U-100 to U-500 regular insulin using an Omnipod DASH pump because increasing insulin requirements exceeded the practical capacity of its 200-unit reservoir. His total daily insulin requirement was approximately 245 units (77 units basal and 50–65 units per meal), and he was also receiving metformin 700 mg twice daily.
Due to recurrent hypoglycemia, the patient transitioned to an Omnipod 5 automated insulin delivery system during a 4-day hospitalization while continuing U-500 insulin. Because the pump was designed for U-100 insulin, insulin doses and delivery rates were divided by 5, while insulin-to-carbohydrate ratios and correction factors were multiplied by 5. Initial settings included a maximum basal rate of 1.4 pump-displayed units/hour, maximum bolus of 20 pump-displayed units, insulin-to-carbohydrate ratio of 5 g/unit, correction factor of 60 mg/dL/unit, active insulin duration of 6 hours, and glucose targets of 120 mg/dL during the day and 130 mg/dL overnight. The patient received education on standardized meal announcements, activity mode, and avoiding independent pump-setting adjustments to minimize dosing errors.
At Omnipod 5 initiation, U-500 insulin was supplied in vials. Following vial discontinuation in France in February 2026, the patient received additional training on withdrawing U-500 insulin from pens using syringes supplied with the Omnipod kits.
Over 12 months, the patient completed five in-person visits and three teleconsultations, with pump settings progressively adjusted based on continuous glucose monitoring (CGM) and pump data to address hypoglycemia and postprandial hyperglycemia. Time in range increased from 75% to 79.1%, while time below range decreased from 9% to 5.7%, with 0.4% of readings below 54 mg/dL. Automated mode was active more than 95% of the time, and the patient reported fewer symptomatic hypoglycemic episodes, although occasional episodes persisted during overnight shifts. No severe hypoglycemia, diabetic ketoacidosis, clinically significant ketosis, or recurrent technical issues suggestive of U-500 insulin incompatibility were reported. A few insulin-leakage events occurred with a subsequently recalled defective pod batch. Total daily insulin requirements increased slightly to approximately 252 units/day. However, outcomes were not separately reported for the period following the transition from U-500 vials to pens, limiting conclusions about pen-to-pump transfer safety.
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Study Author Conclusions
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In selected people with T1D and severe insulin resistance, carefully supervised off-label use of U-500R with AID may therefore reduce hypoglycemia exposure while preserving patch-pump therapy despite very high insulin requirements. Safe implementation requires unambiguous dose conversion, conservative and individualized settings, structured education, and close review of CGM and pump data. This strategy should be regarded as a pragmatic option when better-matched alternatives are unsuitable, rather than as evidence that U-500R is ideally suited to current AID algorithms.
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