Abstract
Purpose:
The purpose of the study was to identify demographic factors associated with continuous glucose monitor (CGM) and automated insulin delivery (AID) use among adolescents with type 1 diabetes and to explore why adolescents may start and stop using CGMs.
Methods:
Adolescents ages 13 to 17 and caregivers completed demographic and device use surveys at baseline for a randomized trial of a behavioral intervention conducted at 2 large medical centers in the United States. This study is a secondary analysis of the demographic and device use data.
Results:
The study sample consisted of 198 participants ages 13 to 17, 58% female, 57% non-Hispanic White, 24% non-Hispanic Black, 19% other race and ethnicity. Eighty-one percent of adolescents were using CGM, and 10% reported past use. Forty percent of adolescents reported taking CGM breaks ranging hours to weeks. Higher CGM use was found in higher income families (>$90 000). No difference in CGM use was observed related to race or ethnicity.
Conclusions:
These findings suggest CGM use is increasing even among adolescents, a group that historically has had the lowest device use. However, adolescents often take CGM breaks, and it is not clear if they adjust their diabetes management during these times. It is important for providers to understand when and why patients may take CGM breaks so education about diabetes management while off CGM can occur. Further investigation into management during CGM breaks, particularly in those using an AID system, is needed.
Continuous glucose monitors (CGMs) have transformed diabetes management, improving glycemic outcomes and quality of life for many people living with type 1 diabetes (T1D),1-4 but adolescents are the age group least likely to use CGMs and least likely to meet glycemic targets, making CGM use in adolescents an important and necessary area of investigation. 5 CGMs are wearable devices that measure interstitial glucose levels and transmit data to users’ smartphones or readers. These data can inform decisions related to insulin dosing, exercise, and food choice, and consistent use is needed for optimal glycemic benefits.6,7 Increasingly, glucose data from CGMs are being integrated with insulin pumps in automated insulin delivery (AID) systems, some of the most recent advances in diabetes treatment. Although AID systems have the ability to improve glycemic outcomes, 8 these devices can only adjust insulin delivery when a CGM is actively transmitting data. Therefore, identifying barriers to CGM use is important because consistent use has the potential to increase time in range, decrease hypoglycemia, and lower A1C.1-3
Prior studies have shown that adolescents do not use CGMs consistently; they have lower rates of use and higher rates of discontinuation than other age groups. 9 Consequently, they are less likely to realize glycemic benefits of CGM use, including more time in range (70-180 mg/dl, 3.9-10 mmol/l) with less hypoglycemia. 3 Although previous research has identified barriers to CGM use (insurance coverage, cost, skin/adhesive problems, difficulty calibrating), 10 findings from studies that included older generations of CGMs may be out of date because newer devices tout longer wear time, smaller size, and no or minimal calibration. 11 Additionally, many early CGM studies showed limited benefit in adolescents due to decreased CGM use over time. 9 Thus, it is important to understand why adolescents who initiated wearing a CGM may choose to discontinue use and how their diabetes management changes after they stop wearing a CGM. Given these updates in devices and a push to increase CGM use in all populations, 12 current information about device use in adolescents is needed to optimize use and health outcomes in this population.
Among young adults with T1D, disparities in device use and diabetes outcomes have been reported, particularly among lower-income and non-Hispanic Black populations. 13 A recent analysis using data from a national sample indicated that adolescent CGM and pump users were more likely to have a yearly household income ≥$150 000, private health insurance, and at least 1 parent with a college education than nonusers. 14 Additionally, CGM use was highest among non-Hispanic White patients and lowest among non-Hispanic Black patients, even after adjusting for insurance status.13,15 Furthermore, a recent study among both children and adults with T1D found implicit bias among providers when recommending CGM and insulin pumps based on their patients’ race, ethnicity, and type of insurance. 16 Similar disparities in insulin pump use have been reported, with these technologies used the least in the non-Hispanic Black population. 13 These disparities in CGM and insulin pump use among adolescents are striking, but they may not reflect current levels of use because CGM uptake has rapidly increased since most of these data were collected.5,17 The American Diabetes Association now recommends considering CGM use at or shortly after diagnosis, 12 which may lead to increased CGM use regardless of race, ethnicity, income, and insurance type. Additionally, over the last 5 years, AID systems have become more available, 18 and it is not known whether disparities in use related to race/ethnicity or income are seen with these systems. Updating understanding of demographic factors associated with CGM and AID systems use is critical to increasing access of these devices to all people with T1D.
Given the rapid evolution of diabetes devices and new practice guidelines 12 encouraging CGM use shortly after diagnosis of diabetes, it is important to understand current patterns of CGM and AID system use among adolescents with T1D. The purpose of this study was to identify demographic factors associated with device use, including race/ethnicity, family income, and caregiver education. In addition, adolescents’ reasons for initiating and stopping CGM use were explored to identify targets for future interventions and to help guide patient education during CGM “breaks.”
Methods
Research Design
The current study is a secondary analysis of baseline data from 198 adolescents with T1D and their caregivers participating in a multisite randomized trial of a behavioral intervention (clinicaltrials.gov identifier: NCT03845465). 19 To be eligible for the behavioral intervention trial, adolescents had to be age 13 to 17, diagnosed with T1D for at least 12 months, have their own cell phone, and demonstrate at least moderate diabetes distress on the Problem Areas in Diabetes – Teen survey ( ≥ 34). 20 Adolescents and caregivers had to speak and read English, and adolescents could not have another medical condition that interfered with diabetes management. The purpose of the randomized trial was to evaluate the effects of a positive psychology intervention on diabetes distress and glycemic outcomes. Recruitment and enrollment of the behavioral intervention trial happened within the outpatient pediatric diabetes clinic at Vanderbilt University Medical Center and Children’s National Hospital. Participants were approached during routine clinic visits, and if eligibility criteria were confirmed, they were provided more information about the study. Assent was obtained from all participants, and consent was obtained from caregivers. After enrolling in the behavioral intervention, adolescents and caregivers completed demographic and diabetes device use surveys on research iPads as part of baseline data collection. Their responses were entered directly into REDCap, a secure research database, and they were saved using participant ID number within REDCap.
This secondary study analyzed the demographic and diabetes device use surveys to determine demographic variables associated with device use in adolescents with T1D. The secondary analysis also examined reasons why adolescents might stop using CGM (CGM breaks). The randomized trial of the positive psychology intervention did not explore demographic patterns of device use. It also did not examine reasons why adolescents might take CGM breaks. The secondary analysis exploring device use in adolescents with T1D is based on a new research question, and the analyses do not overlap with the positive psychology intervention.
Measures
Diabetes device use survey
The diabetes device use survey was developed by the study team to assess use of CGMs and insulin pumps (including AID systems) and barriers to use. Two versions of the device use survey were created—one for adolescent participants and one for caregivers. Examples of questions (participant survey) include: “Do you currently use a continuous glucose monitor (CGM)?”; “What information would have been helpful prior to starting the CGM?”; “How many days per week do you usually wear a CGM?”; and “What are some of the reasons you would use your CGM less than 7 days per week?” Caregivers completed the same questions related to their adolescents’ current use; however, because caregivers are typically in charge of ordering devices and scheduling pediatric diabetes appointments, caregiver responses were used for analyses related to starting these devices and to classify participants as current CGM or AID system users.
Area Deprivation Index
Although demographic variables such as race, ethnicity, education level, and income are associated with health outcomes, residing in a disadvantaged area has also been associated with worse health outcomes. 21 The Area Deprivation Index 21 (ADI) is a measure designed by the University of Wisconsin School of Medicine and Public Health to assess neighborhood disadvantage based on multiple socioeconomic factors, including housing quality, education access, and employment. These socioeconomic factors have been linked to worsened health outcomes, higher rates of chronic disease, and greater health care costs. 21 Home addresses provided by caregivers were used to derive national percentile for each participant, ranging from 1 to 100, with lower scores indicating lower levels of deprivation and higher values indicating higher levels of deprivation. Using the ADI allowed for exploration into neighborhood-level factors associated with CGM use.
Demographic survey
During enrollment for the behavioral intervention, caregivers reported demographic information, including caregiver race, ethnicity, sex, education level, and annual household income. Caregivers also reported their child’s race, ethnicity, and sex.
Glycemic indicators
Point-of-care A1C values were extracted from adolescents’ medical records when available. If a point-of-care A1C was not available at the time of enrollment, participants completed a Coremedica mail-in A1C kit, or a glucose management indicator (GMI) was estimated from the adolescent’s available CGM data. Prior research has shown mail-in kits and GMI to be comparable to a point-of-care A1C.22,23
Data Analytic Plan
Version 28.0 of SPSS Statistics was used to conduct analyses. Nonparametric tests were used in all analyses. Chi-square and Mann-Whitney U tests were employed to assess demographic factors and A1C levels associated with caregiver-reported CGM use. CGM use was compared between non-Hispanic White (NHW), non-Hispanic Black (NHB), and other racial and ethnic groups.
Results
The study sample consisted of 198 adolescents with T1D age 13 to 17 (58% female, Mage = 15.3 ± 1.4 years, MT1D duration = 6.4 ± 3.7 years since diagnosis, MA1C = 9.2% ± 2.1% [77 mmol/mol], 57% NHW, 24% NHB, 19% other race and ethnicity; Table 1) and their caregivers (86% female, Mage = 45.7 ± 7.3 years, 66% NHW, 21% NHB, 13% other race and ethnicity, 61% college graduate or higher, 50% having a combined household income ≥$90 000; Table 2).
Descriptive Statistics for Child Demographic Variables
Descriptive Statistics for Caregiver Demographic Variables
Reported CGM Use
Based on caregiver reports, 81% (n = 161) of adolescents were currently using CGM, 10% (n = 20) had previously used a CGM, and 9% (n = 17) had never used a CGM. CGM use at baseline increased significantly over the study period, χ2(1, N = 198) = 7.23, P = .003, from 69% of participants in the first year of enrollment (December 2019-November 2020), to 87% in the second year of enrollment (December 2020-November 2021), and to 83% in the final enrollment period (December 2021-June 2022). When asked how they started using the devices, 61% of current and past CGM users reported starting their CGMs at their diabetes clinic, 34% started their CGMs at home, and 5% started their CGMs with a company educator.
Barriers to CGM Use
Caregivers and adolescents who were using or had previously used a CGM were asked what they would have wanted to know about CGMs prior to starting the device. Adolescents and caregivers reported wanting more information about accuracy, how the CGM works, how the CGM is worn, and cost (Table 3). Adolescents reported discontinued use of a CGM due to pain/discomfort, not liking to wear them during exercise or school, not liking having them on their bodies, and problems with the adhesive (Table 3).
Description of Barriers to CGM Use
Abbreviation: CGM, continuous glucose monitor.
CGM Breaks
Of adolescent CGM users, 28% (n = 44) reported wearing their device less than 21 days/month, and 72% reported wearing their CGM 22 to 31 days per month (Table 4). When asked about CGM breaks, 64 of 160 reported taking CGM breaks (40%). Reasons for taking a CGM break included vacation, skin irritation, physical activity, technology issues, CGM falling off, or problems with supplies/insurance approval (Table 5). Many adolescents reported taking a break from their CGM between sensor changes. CGM breaks were reported to last from a few hours (30%) to a week or longer (13%; Table 5), with 63% of the adolescents who reported taking breaks from their CGM endorsing more problems with high or low blood glucose when they did not wear their CGM. During CGM breaks, 35% of adolescents reported checking their blood glucose 2 to 3 times per day, and 19% of adolescents reported checking blood glucose 0 to 1 time per day.
Diabetes Device Use
Abbreviations: AID, automated insulin delivery; CGM, continuous glucose monitor.
Reasons for CGM Breaks
Abbreviation: CGM, continuous glucose monitor.
Demographic Variables Associated With CGM Use
There were no significant differences in CGM use by study site (82% vs 81%; χ2 = 0.02; P = .893). Adolescents whose caregiver had an education level less than a college degree were significantly less likely to use a CGM (73%) compared to those with college degrees or higher (87%; χ2 = 5.98; P = .015). Based on a median split of the household income of the sample, CGM use was significantly lower among adolescents whose family income was <$90 000/year (76%) than those with higher income (87%; χ2 = 1.02; P = .045). There was no difference in CGM use related to child age or reported sex. There were no significant differences in CGM use between NHW, NHB, and adolescents of other races and ethnicities (χ2 = 1.08; P = .581). There was no difference in national ADI scores between CGM users and nonusers.
Demographic Variables Associated With AID System Use
Based on caregiver reports, 24% (n = 47) of adolescents were using an AID system for insulin delivery. There were no significant differences in AID use by site: 28% vs 19% (χ2 = 1.80; P = .18). In addition, no significant differences were observed in the use of AID systems related to caregiver education level, annual household income (when examined above and below the median income of the sample), adolescent age, sex, race, ethnicity, or national ADI score.
Glycemic Outcomes in Device Use
Current CGM users had a significantly lower A1C than current nonusers, U = 1813, P = .023. CGM users had a mean A1C of 9.0% ± 2.1 (75 mmol/mol), and nonusers had a mean A1C of 9.9% ± 2.2% (85 mmol/mol). Likewise, AID system users had a significantly lower A1C than nonusers, U = 2390, P = .032. AID system users had a mean A1C of 8.7% ± 2.3% (72 mmol/mol), and nonusers had a mean A1C of 9.3% ± 2.1% (78 mmol/mol).
Discussion
CGMs and AID systems have dramatically changed diabetes management, improving A1C, time in range, and hypoglycemia for many people with T1D2-4,8; however, for individuals to realize optimal benefit from these devices, they must be worn consistently. 6 Previous studies have demonstrated that adolescents are the least likely age group to wear CGMs, 5 but the reasons why adolescents may temporarily discontinue CGM use (termed a “CGM break” in this study) and how their diabetes management may change during this time has not been previously described. This study examining demographic factors associated with CGM use in a diverse sample of adolescents with T1D found that the majority of adolescents were using CGM (81% of participants); however, nearly one-third of adolescents report wearing their CGM <21 days per month, which has the potential to affect glycemic outcomes, especially in those using AID systems. Although AID systems will deliver insulin if a CGM is not worn, adolescents and their caregivers may not realize that AID systems will not work as intended without a CGM. Increased adolescent education on AID systems may be needed to improve their understanding about how CGM and AID devices work, which could translate into increased use with the potential for improved glycemic outcomes.
In the current study, 28% of adolescents self-reported wearing CGM less than 21 days in the last month and endorsed both voluntary (vacation, physical activity, etc) and involuntary (sensor failure, sensor fell off, etc) reasons for these CGM breaks. Studies have shown that although a CGM can be effective in decreasing hypoglycemia and increasing time in range,2-4 it must be worn consistently to achieve these benefits. 6 In addition, 54% of adolescents in the current sample reported checking blood glucose levels less than 2 to 3 times per day when not wearing a CGM, which is much lower than the current recommendations of monitoring 6 to 10 times per day. 12 Taken together, these findings suggest that although adolescents are increasingly using CGMs, they may not be experiencing the clinical benefits that are associated with increased use.
In the current study, higher levels of caregiver education and higher household income were associated with greater CGM use, similar to previous findings. 14 The median household income among participants in this study was $90 000, and participants with income above the median were more likely to use CGMs. Increased level of caregiver education was also associated with higher CGM use; specifically, participants with caregivers who held a college degree or higher were more likely to wear a CGM (73% of adolescents whose caregiver had less than a college education reported wearing a CGM, whereas 87% of adolescents whose caregiver had a college education or higher reported wearing a CGM). There are several possible reasons for these differences, including but not limited to increased ability to pay for CGMs and differences in familiarity/knowledge of CGMs. Although Medicaid (public health insurance) is increasingly covering CGMs,24,25 private insurance plans often have high deductibles, which may make CGMs too expensive for certain populations. These findings suggest that CGMs may not be affordable for middle-income populations (those with a household income lower than $90 000 who do not quality for public health insurance).
In contrast to previous studies, significant associations between CGM use and race and ethnicity were not observed.13,15 This is notable given the diverse racial and ethnic representation of participants in this study. These findings suggest that in these 2 large academic medical centers, patterns of CGM use may be changing compared to previously reported findings of lower use among minoritized racial and ethnic groups. It is not known whether changing guidelines for CGM initiation (ie, initiation of CGM shortly after diagnosis 12 ) and use are driving more equitable CGM use or whether changes in insurance coverage may partially explain these findings. It is also notable that CGM use among enrolled participants increased over the course of the study, suggesting that this technology has become more accessible to patients with T1D than in previous years. Lastly, CGM use was not significantly different based on national ADI scores indicating residence in a lower deprivation community, which may reflect changing insurance coverage for CGMs, increased awareness of CGM technologies, or increased provider comfort and prescription of these devices.
This study also reports on the use of AID systems, which are becoming increasingly available. No significant differences were found among adolescents who did and did not use AID systems with respect to race, ethnicity, income, caregiver education, or residence in a lower deprivation community. Although the total number of participants reporting AID use was low, this is a notable finding given that AID systems are relatively new technologies without much data available related to current patterns of use. The questions about AID use were based on self-report, and it is possible that participants/caregivers were not aware of whether they were using an AID system (given that some of these systems only required a system upgrade to automate insulin delivery).26,27 Recent literature suggests that insulin pump use is increasing among adolescents with T1D in the United States; however, these data also have found inequity in pump use (not specific to AID systems), with lower use in non-White youth, lower-income youth, and in those whose parents hold less than a bachelor’s degree. 28 Additional studies are needed to understand how AID systems are being prescribed and used among youth in the United States.
Limitations of this study include reliance on self-report/caregiver report of CGM/AID system use, which may not reflect actual use, and limited response to some of the questions within the survey. Adolescent participants of the positive psychology behavioral intervention were enrolled if they reported moderate levels of diabetes distress, which, in turn, could affect participants’ diabetes device use (and self-report about CGM use). No data about patient insurance status were collected for the intervention, so analysis of the impact of public or private insurance on CGM or AID use was not possible. Finally, although this study was conducted in 2 large academic medical centers, findings from these centers may not represent CGM and AID system use in smaller rural communities.
Implications for Patient Care and Education
Many studies indicate that increased CGM use is associated with improved time in range and decreased hypoglycemia.2-4 Previous studies of CGM in youth were limited by lower CGM use (especially when compared to adult studies) and therefore did not show the same glycemic benefits compared to adult studies. The current study shows that although most adolescents reported using CGM, many were not consistently wearing these devices. AID systems rely on CGM data to automate insulin delivery, and without CGM data, these insulin pumps operate as a traditional insulin pump (ie, no automated adjustments to insulin dosing). Although several studies demonstrate the potential for AID systems to improve glycemic outcomes, CGMs must be worn consistently to achieve these benefits. It is not yet clear how CGM breaks may affect glycemic outcomes—particularly in those using AID systems. These findings highlight the need for families to receive education about the importance of using a glucometer to monitor blood glucose levels while off CGM and an understanding that AID systems will work differently when CGM is not in use.
Although 81% of adolescents in this study reported wearing CGM, nearly one-third also reported wearing their CGM <21 days in the last month. Increasingly, CGM devices are used together with AID systems, and when individuals are not wearing their CGM, insulin delivery can be affected. More studies—including qualitative studies—are needed to determine how adolescents with T1D manage their diabetes during CGM breaks and reasons for voluntary (patient decision) versus involuntary (insurance problem, delay in shipment of supplies, etc). In addition, youth starting on insulin pump therapy within the last few years may not be familiar with insulin pumps that do not have AID, and education about how these insulin pumps work with or without a CGM is important. Adolescence is a period of development that has historically been associated with poor glycemic outcomes, and although diabetes devices have the potential to improve these outcomes, the rapidly changing landscape of diabetes technology makes it critically important to understand how adolescents are using these devices.
Footnotes
Authors’ Contributions
SG researched and analyzed data, wrote, reviewed, and edited the manuscript. AP wrote, reviewed, and edited the manuscript. RS was a site PI and analyzed data and reviewed and edited the manuscript. SJ was also a site PI and analyzed data and reviewed and edited the manuscript. KD wrote, reviewed, and edited the manuscript. KD is the guarantor of the work and, as such, had full access to all of the data in the study and takes responsibility for the integrity of the data and accuracy of the data analysis.
Declaration of Conflicting Interests
The authors declare that there is no conflict of interest.
Funding
This work was supported by the National Institutes of Health (R01DK121316). KD was supported by the Katherine Dodd Faculty Scholars Program.
