Advanced hybrid closed-loop systems (AHCL) have demonstrated long-term benefits in all people with diabetes (PWD). However, unpublished reports suggest that PWD using multiple daily injections (MDI) might delay activation of AHCL because of concerns around managing pump therapy.


We retrospectively studied first 90 days of pump activation in MDI users with type 1 diabetes transitioning to t:slim X2™ insulin pump with Control-IQ® technology. Participants (age 34±20, 52% female) were categorized into 3 groups: G1 initiated Control-IQ technology within 2 days of pump start, G2 initiated between 2-14 days, and G3 initiated within 15-90 days. Hypoglycemia and time in range (TIR) sensor glycemic (SG) metrics for Control-IQ technology use were retrieved from Tandem’s t:connect® web application. Group differences were analyzed using Mann Whitney U and Kruskal-Wallis tests.


81% of users, initiated Control-IQ technology within 2 days of pump start (G1, n=14222) followed by G2 (14%, n=2448), and G3 (5%, n=870). Groups did not differ on baseline HbA1c. With Control-IQ technology, no differences were noted for SG<54mg/dL (median (IQR): G1=0.13(0.04-0.3), G2=0.12(0.04-0.31), G3=0.13(0.04-0.32) and SG<70mg/dL: G1=0.87(0.36-1.8), G2=0.84(0.38-1.7), G3=0.89(0.37-1.72). There were no differences between G1 and G2 on TIR (70-180mg/dL): G1=68.6(57.8-78.1), G2=69.5(59.1-79.1). However, G3 showed significantly lower TIR: 66.6(55.6-77.9) (p=0.003). Overall, 99.5% of participants continued to use Control-IQ technology at the time of this analysis.


95% of MDI users (G1, G2) successfully initiated Control-IQ technology within 14 days of pump start. While all groups experienced success with Control-IQ technology, G3 showed lower TIR with delayed initiation.

Median Sensor Time in Range (70-180 mg/dL)

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Responsible Use of Control-IQ Technology

Even with advanced systems such as the t:slim X2 insulin pump with Control-IQ technology, patients are still responsible for actively managing their diabetes. Control-IQ technology does not prevent all high and low blood glucose events. The system is designed to help reduce glucose variability, but it requires that patients accurately input information, such as meals and periods of sleep or exercise. Control-IQ technology will not function as intended unless all system components, including CGM, infusion sets and pump cartridges, are used as instructed. Importantly, the system cannot adjust insulin dosing if the pump is not receiving CGM readings. Since there are situations and emergencies that the system may not be capable of identifying or addressing, patients should always pay attention to their symptoms and treat accordingly.

1. Petrovski G, et al. One-year experience of hybrid closed-loop system in children and adolescents with type 1 diabetes previously treated with multiple daily injections: drivers to successful outcomes. Acta Diabetol. 2021;58:207-213.
2. Boughton CK, et al. Training and support for Hybrid Closed-Loop Therapy. J Diabetes Sci Technol. 2022;16:218-223.
3. Breton MD, Kovatchev BP. One Year Real-World Use of the Control-IQ Advanced Hybrid Closed-Loop Technology. Diabetes Technol Ther. 2021;23(9):601-608.
4. Barnard K, et al. Patient-Reported Outcomes and Continuous Glucose Monitoring: Can we do better with artificial pancreas devices? Diab Care. 2015;38(5):e70.

Important Safety Information

RX ONLY. The t:slim X2 pump and Control-IQ technology are intended for single patient use. The t:slim X2 pump and Control-IQ technology are indicated for use with NovoLog or Humalog U-100 insulin.

t:slim X2 insulin pump : The t:slim X2 insulin pump with interoperable technology is an alternate controller enabled (ACE) pump that is intended for the subcutaneous delivery of insulin, at set and variable rates, for the management of diabetes mellitus in people requiring insulin. The pump is able to reliably and securely communicate with compatible, digitally connected devices, including automated insulin dosing software, to receive, execute, and confirm commands from these devices. The t:slim X2 pump is indicated for use in individuals six years of age and greater. Control-IQ technology: Control-IQ technology is intended for use with a compatible integrated continuous glucose monitor (iCGM, sold separately) and ACE pump to automatically increase, decrease, and suspend delivery of basal insulin based on iCGM readings and predicted glucose values. It can also deliver correction boluses when the glucose value is predicted to exceed a predefined threshold. Control-IQ technology is intended for the management of Type 1 diabetes mellitus in persons six years of age and greater.

WARNING: Control-IQ technology should not be used by anyone under the age of six years old. It should also not be used in patients who require less than 10 units of insulin per day or who weigh less than 55 pounds.

Control-IQ technology is not indicated for use in pregnant women, people on dialysis, or critically ill patients. Do not use Control-IQ technology if using hydroxyurea. Users of the t:slim X2 pump and Control-IQ technology must: use the insulin pump, CGM, and all other system components in accordance with their respective instructions for use; test blood glucose levels as recommended by their healthcare provider; demonstrate adequate carb-counting skills; maintain sufficient diabetes self-care skills; see healthcare provider(s) regularly; and have adequate vision and/or hearing to recognize all functions of the pump, including alerts, alarms, and reminders. The t:slim X2 pump, transmitter, and sensor must be removed before MRI, CT, or diathermy treatment. Visit for additional important safety information.