Incidence of type 1 diabetes (T1D) is increasing in different ethnic groups. Given the rapid evolution of insulin delivery systems, it is important to evaluate their performance in diverse populations. The Control-IQ Observational (CLIO) Study is an IRB-approved, single-arm, longitudinal study evaluating real-world use of the Control-IQ system in people with T1D (PWT1D) who had been prescribed the Tandem t:slim X2 insulin pump with Control-IQ technology. We evaluated relationships between glycemic metrics, diabetes-specific items, and demographic variables at baseline and 3 months after study start for adult participants who had uploaded at least 21 days (21d) of Control-IQ feature usage data to Tandem’s t:connect® web application and had ≥75% CGM use during this time. Impact of baseline factors on glycemic outcomes were analyzed using generalized linear models. In all, 1094 PWT1D (963 Caucasians, 72 Hispanics, 45 African Americans, 25 Asians) were included in the analysis. African Americans had the highest HbA1c at baseline (8.1%) in contrast to the Caucasian majority (7.3%). Glucose Management Indicator (GMI) at 21d reflected significant glycemic improvement across all ethnic groups with Asians showing the lowest GMI (6.77%) followed by Caucasians (6.98%). At 21d, the sensor time in range (TIR) (median) of African Americans (62.7%, IQR=53.4-74.7) was significantly lower than for Caucasians (75.1%, IQR=70.3-81.0) while controlling for age, gender, reported exercise, annual income, and prior therapy (p=0.004). Baseline HbA1c was the key factor predicting TIR at 21d followed by exercise, annual income, and multiple daily injections (prior therapy). We identified disparities in glycemic outcomes across socioeconomic and demographic groups at baseline that remained after initiating an automated insulin delivery system. Nevertheless Control-IQ technology significantly improved glycemic outcomes for all ethnic groups.


S. Habif: Employee; Self; Tandem Diabetes Care. H. Singh: Employee; Self; Tandem Diabetes Care. L. Mueller: Research Support; Self; Dexcom, Inc., Tandem Diabetes Care. M. L. Manning: Employee; Self; Tandem Diabetes Care. K. N. White: Employee; Self; Tandem Diabetes Care. S. A. Leas: Employee; Self; Tandem Diabetes Care. E. S. Aronoff spencer: None. B. Dokken: Employee; Self; Tandem Diabetes Care, Stock/Shareholder; Self; Tandem Diabetes Care. E. Aronoff spencer: None.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at