• Center on Health Equity and Access
  • Clinical
  • Health Care Cost
  • Health Care Delivery
  • Insurance
  • Policy
  • Technology
  • Value-Based Care

T:Slim X2 Insulin Pump Use Safe in Pregnant Individuals With T1D, but Efficacy Varies


The pump had varying success in reaching recommended glycemic targets among the study participants with type 1 diabetes (T1D).

Tandem t:slim X2 insulin pumps were safely used during pregnancy in individuals with type 1 diabetes (T1D) but had variable success in achieving glycemic targets, according to a study published in Cureus.

T1D has been associated with an increased rate of adverse outcomes during pregnancy, and pregnant individuals are at greater risk of developing complications such as hypoglycemia due to strict glycemic control.

Type 1 diabetes | Image Credit: © Svetlana - stock.adobe.com

Type 1 diabetes | Image Credit: © Svetlana - stock.adobe.com

These risks have indicated the need for further research on the safety and glycemic control potential of automated insulin delivery (AID) systems, such as new insulin pump technology that could aid patients with treatment.

This retrospective, observational study was conducted to analyze the safety and efficacy of the Tandem t:slim X2 insulin pump in pregnant individuals with T1D. The device has 2 main operation modes that vary in capabilities: a predictive hypoglycemia suspension system called BIQ and a closed loop system called control IQ (CIQ).

Data were obtained through analyzing monthly records of individual CGM readings to calculate the percentage of time spent within, above, and below the recommended glycemic range for pregnant individuals (63-140 mg/dL). In total, 8 individuals were included in the study; 6 used CIQ and 2 used BIQ, the investigators wrote.

Mean (SD) hemoglobin A1c (HbA1c) during pregnancy was 6.1% (0.8%); for CIQ users, 6.1% (0.7%), and for BIQ users, 6.0% (1.1%), according to the study data. In CIQ participants, the mean (SD) sensor glucose was 127.6 (16.8) mg/dL, whereas it was 118.4 (16.4) mg/dL in BIQ users.

Participants using CIQ had a mean (SD) time in pregnancy range (TIR) of 67.9% (15.7%), time above range (TAR) of 30.6% (16.0%), and time below range (TBR) of 1.5% (1.4%), the study results indicated. BIQ users had a mean (SD) TIR of 68.1% (12.0%), TAR of 25.9% (12.3%), and TBR of 6.1% (2.4%).

The mean (SD) total daily dose (TDD) of insulin increased by 96.1%, from 51.1 (27.1) units in the first trimester to 100.2 (53.1) units in the third trimester, the investigators found. CIQ users received 99.7 (56.8) units in the third trimester; 1 BIQ participant was lost to follow-up partway through the third trimester, but the other required a mean of 103.5 units.

Notably, only 2 CIQ users used exercise in combination with the device, and sleep duration did not increase or decrease consistently across trimesters. At the same time, multiple participants had sleep activity durations over 12 hours, which the investigators believe shows that participants were using the feature during the daytime.

There were lower TIR values seen in participants with higher basal insulin usage, which demonstrated a negative correlation between the basal-to-bolus insulin ratio and TIR (r = –0.415), the investigators found. Outcomes during pregnancy were documented: Half of the cohort had pre-eclampsia, half of the study participants had early deliveries before 37 weeks gestation, and all participants’ children needed admission to the neonatal intensive care unit.

Overall, the analysis of data indicated challenges in the care of pregnant individuals with T1D using technology that was not originally designed for pregnancy, the investigators discussed. Paradoxically, patients had increasing TBR and TAR and decreasing TIR by the end of pregnancy although frequent and numerous pump setting changes were made.

“These differences in care engagement highlight significant challenges in optimizing the care of pregnant individuals with diabetes,” the investigators noted.

The adverse pregnancy outcomes that were frequent across the cohort could be explained by the difficulties in achieving recommended pregnancy glycemic goals, according to the investigators. Further, they discussed the prospect of elevated prepregnancy body mass index being a contributing factor to a higher incidence of pre-eclampsia.

AID technology is becoming more common, and its use in pregnancy has been increasing in conjunction with that trend. The investigators agreed on the need for larger-scale studies to better understand the differences in CIQ and BIQ efficacy, as well as strategies to adapt these technologies for use in pregnancy.

“Until these advances are made, practitioners must understand the details of insulin pump algorithms to provide individualized care for pregnant patients with T1D,” the investigators concluded.


Nandam N, Thung S, Venkatesh KK, et al. Tandem t:slim X2 insulin pump use in clinical practice among pregnant individuals with type 1 diabetes: a retrospective observational cohort study. Cureus. 2024;16(1):e52369. doi:10.7759/cureus.52369

Related Videos
Video 10 - "Bronchiectasis Exacerbation Management"
video 10  - "Developing Practical Solutions to Improve Cardiovascular Care"
video 10  - "Developing Practical Solutions to Improve Cardiovascular Care"
Video 6 - "Optimal Approaches to Diagnostic Testing for Type 1 Diabetes Mellitus"
Video 13 - "Concluding Thoughts on Ph+ ALL Treatment"
Video 12 - "The Future of Ph+ ALL Treatments"
dr lawrence eichenfield
dr krystyn van vliet
Raajit Rampal, MD, PhD, screenshot
Michael Morse, MD, FACP, MHS, Duke Cancer Center
Related Content
© 2024 MJH Life Sciences
All rights reserved.