Abstract
OBJECTIVE
The Teamwork, Targets, Technology, and Tight Range (4T) Exercise Program evaluated physical activity patterns across the first year of type 1 diabetes diagnosis and whether physical activity was associated with changes in glucose outcomes in the 24 h following physical activity.
RESEARCH DESIGN AND METHODS
The 4T Exercise Program started newly diagnosed youth with type 1 diabetes on a continuous glucose monitoring (CGM) system and physical activity tracker around 1 month postdiagnosis. A subset of youth opted to participate in up to four quarterly structured exercise education sessions to increase their knowledge around safe physical activity.
RESULTS
Ninety-eight youth with type 1 diabetes (median [interquartile range (IQR)] age of 13 [12–15] years, 45% female, 44% non-Hispanic White) completed the study. Compared with sedentary days, days with ≥10 min of vigorous-intensity physical activity were associated with an increase in time in range (TIR) of 2.3% (1.4–3.2%; P < 0.001), a decrease in time above range (TAR) of 3.1% (2.2–4.0%; P < 0.001), and an increase in time below range (TBR) of 0.8% (0.6–0.9%; P < 0.001) in the 24 h following physical activity. From 1–3 months to 10–12 months postdiagnosis, the median (IQR) step count increased by 1,134 (445–1,519) steps per day (P < 0.001), while daily moderate-to-vigorous physical activity increased by 11 (2–23) min per day (P < 0.001).
CONCLUSIONS
In the 24 h following physical activity as compared with sedentary days, TIR improved, TAR was lower, and TBR remained within clinical target recommendations. For youth with new-onset type 1 diabetes, each structured exercise education session was associated with a further 0.79% increase in TIR.
Graphical Abstract
Introduction
Current standards of care for diabetes include recommendations that individuals with type 1 diabetes (T1D) should reduce sitting time and engage in 1) 60 min/day of moderate-to-vigorous physical activity (MVPA; 3–6 METs) for youth or 2) 150 min/week of MVPA spread over at least 3 days/week for adults (1). These guidelines also acknowledge that performing vigorous-intensity activity (i.e., >6 METs; 75 min/week) is sufficient for younger people who are able to exercise at this intensity. However, the population with pediatric T1D is 56% less likely to meet these guidelines compared with their peers without diabetes (2), and managing glycemia around exercise remains a major barrier (3,4). The various consensus guidelines on exercise self-management in T1D (5,6) are based on limited clinical research studies of select subpopulations such as elite athletes, young adults with long-standing diabetes, and those with higher levels of education or physically active at baseline. However, recommendations are often complex and difficult to follow, and have recently been shown to have low rates of uptake (7). Translation and implementation of these guidelines for the general population with T1D is urgently needed, particularly for those who are newly diagnosed or attempting to increase physical activity levels while optimizing diabetes self-management strategies.
Many individuals who are physically active before their T1D diagnosis become less active after diagnosis (8). While often acknowledging that regular activity is important for their physical and mental health (8), newly diagnosed individuals with T1D often report several barriers to exercise, including lack of knowledge and the inability to manage their glucose levels safely and effectively for exercise (8).
As part of the Teamwork, Targets, Technology, and Tight Range (4T) Study, which aims to achieve tight glucose targets in newly diagnosed youth with T1D using a precision medicine approach with remote patient monitoring (RPM) (9), we developed the 4T Exercise Program, designed to educate on the importance of regular physical activity soon after diagnosis and show how to optimize glucose management around exercise using continuous glucose monitoring (CGM) and automated insulin delivery. In a recent study, we demonstrated that the 4T Exercise Program could be delivered remotely and effectively to youth and their families to increase confidence and knowledge around exercise self-management (10). Given the strong associations among physical activity levels, individual health status, and various diabetes-related outcomes (11), initiating exercise education soon after diagnosis may have lifelong benefits.
The overall goal of this research is to assess physical activity patterns across the first year of diagnosis among participants in the 4T Exercise Program and determine whether exercise was associated with favorable changes in glycemic outcomes in the 24 h following an exercise event compared with a matched 24-h period from a sedentary day in newly diagnosed youth with T1D. We hypothesized that days with some level of activity would be associated with increases in percent time in range (TIR), while also associated with decreases in time above range (TAR; >180 mg/dL) and maintaining time below range (TBR; <70 mg/dL) within clinical target guidelines (12).
Research Design and Methods
Study Design
The aim of the 4T pragmatic research study and ancillary 4T Exercise Program is to deliver a team-based approach to clinical care with tighter glucose targets and equitable access to diabetes technology shortly after T1D diagnosis. The study methodology and design are described in detail elsewhere (9,10).
Between June 2020 and August 2024, all youth with T1D at Stanford Lucile Packard Children’s Hospital were offered CGM using the Dexcom G6 or G7 system (Dexcom Inc., San Diego, CA) within the first month of diagnosis (ClinicalTrials.gov registration NCT04336969). In the current paper, we report data from all 4T Exercise Program study 1 and study 2 participants that have completed 12 months of the study duration. The study 1 and study 2 protocols were similar, with the primary differences in study 2 including exercise education being offered to both English- and Spanish-speaking families as well as systematically encouraging youth to attend an automated insulin delivery education class during the initial 3-month period postdiagnosis (13). The HbA1c targets in studies 1 and 2 were <7.0% and 6.5% (53 and 48 mmol/mol), respectively (based on current American Diabetes Association (14) and International Society (ISPAD) (15) guidelines), with CGM-based RPM in the entire study population.
The 4T Exercise Program was approved by the Stanford Institutional Review Board (Stanford, CA; NCT04336969), and informed consent or assent was obtained from youth and parents or caregivers. The inclusion criteria was age 11 to <21 years with a clinical T1D diagnosis seen at Stanford Children’s diabetes clinic, who agreed to CGM data integration for RPM, were willing to wear a physical activity tracker, used a compatible smart device, and were English- and/or Spanish-speaking. Exclusion criteria included diabetes diagnosis other than T1D; diagnosis of diabetes more than 1 month prior to the initial visit; individuals with the intention of obtaining diabetes care at another clinic; individuals who did not consent to CGM use, CGM data integration, RPM, or physical activity tracker use; and individuals ≥21 years of age.
Youth in the 4T Exercise Program were asked to wear a physical activity tracker (Garmin vívosmart 4 or Venu Sq; Garmin Ltd., Olathe, KS) during the study duration. The Garmin vívosmart 4 watch was offered to youth 11–13 years of age, and youth 14 years of age or older had a choice between the vívosmart 4 and Venu Sq. The 4T Exercise Program also offered structured exercise education to a subset of youth and their parents or caregivers. Exercise education modules were delivered quarterly over telehealth, up to a total of four modules, around the following time frames: 1–3 months (module 1), 4–6 months (module 2), 7–9 months (module 3), and 10–12 months (module 4) postdiagnosis. The educational content has been described in more detail elsewhere (10). Exercise education engagement was classified as any participant that completed at least one module (of up to four total) during the study. The 4T Exercise Program was made available to Spanish-speaking families and youth with T1D during study 2, once the education materials were translated into Spanish. Exercise education modules were offered to participants on the basis of available resources (i.e., led by one exercise physiologist, D.P.Z.) with the target of n = 60 to complete education. Participants were offered the choice of 1) structured education plus a physical activity tracker or 2) a physical activity tracker (no exercise education). CGM and physical activity tracker data were collected for all 4T Exercise Program study 1 participants and a subset of study 2 participants—those that completed the full 12-month study duration.
Physical activity data were captured from activity trackers using participant’s daily summaries. Daily activity data of ≥8 h (i.e., heart rate measurements) between 6:00 a.m. and 9:59 p.m. were considered for the analysis, and those that did not have sufficient data were excluded from the analysis. Additionally, only days where any duration of MVPA (MET ≥3) was detected were included in the analysis. The overall summaries of daily steps and MVPA were categorized into four distinct buckets (1–3 months, 4–6 months, 7–9 months, and 10–12 months) corresponding to the approximate windows when the education sessions were completed.
MET official measurements of exercise intensity were used, based on Garmin’s calculation of MET: an estimation based on height, weight, age, and sex. Exercise intensity for each calendar day with valid data was based on the following standardized MET classification criteria (16): 1) a day with vigorous-intensity activity, defined as at least ≥10 min of activity >6 METs, such that it met or exceeded standard of care guidelines for vigorous-intensity activity for diabetes (1); 2) a day that did not have any vigorous intensity activity, but had sustained moderate-intensity activity, defined as ≥30 min of continuous activity between 3 and 6 METs, similar to exercise guidelines for weekly volumes of moderate-intensity activity (1); 3) a day of short-duration moderate-intensity activity if it was not a day of vigorous-intensity activity or sustained moderate-intensity activity but did contain a total of 10–29 min of accumulated moderate-intensity activity (3–6 METs); or 4) a sedentary day if it was not a day of vigorous-intensity, sustained moderate-intensity, or short-duration moderate-intensity activity.
The daily exercise duration for each activity level corresponds to the sum of the duration of the activity records for each day between 6:00 a.m. and 9:59 p.m. Nocturnal (between 10:00 p.m. and 5:59 a.m.) activity was rare and unreliable because the activity tracker was charged regularly overnight, and, therefore, these data were excluded from the analysis.
A minimum of 80% of CGM data in the 24-h period following exercise or sedentary days had to be available to be considered for the analysis. For exercise days, the start of the 24-h period in which the glucose outcomes were assessed corresponded to the clock time where the interval with the maximum duration exercise session (same MET intensity level as the day) ended. To identify a corresponding sedentary 24-h period that has clinical equipoise with exercise days, bootstrap sampling was used to match the pool of exercise end times with each participant’s sedentary days. In addition, we did not restrict CGM data use to mutually exclusive intervals. Thus, two 24-h CGM intervals can overlap and share glucose readings (e.g., an exercise day with the longest recorded event ending at 3:00 p.m. followed by another exercise or matched sedentary day ending at 8:00 a.m. would share 8:00 a.m. to 3:00 p.m. [7 h] of CGM data). Participants were included in the final analysis if they had at least one matched exercise and sedentary day.
Primary outcomes were %TIR, %TAR, and %TBR in the 24 h following exercise in newly diagnosed youth in the 4T Exercise Program. Secondary outcomes included daily step count and daily minutes of MVPA throughout the 4T Exercise Program. Total daily step count and MVPA duration were derived from epoch data from the physical activity trackers. The key exposures of interest were the occurrence and intensity of physical activity, which were assessed daily. Eligible days with any physical activity were matched with randomly selected sedentary days from the same participant. The subsequent 24-h CGM data after physical activity and the corresponding matched sedentary period were used in generalized linear mixed-effects regression models.
Statistical Analyses
For the overall summaries of daily step count and MVPA, box plots with median and interquartile range (IQR) were presented in quarterly time buckets based on the exercise education delivery. To account for both the longitudinal aspect of the design and skewness of step count and MVPA data, changes in daily step count and daily minutes of MVPA over the study period were assessed via Wald tests from generalized linear mixed-effects regression models fitted to the rank-transformed step count and MVPA values. The model included a participant-specific random effect and main effects for study period and exercise education attendance.
To evaluate the impact of exercise on %TIR, %TAR, and %TBR, we used linear mixed-effects models. Specifically, we included a random participant-specific effect to account for the correlation of observations generated by the same participant. The model included indicators of the days’ activity level classification, our primary parameter of interest, representing the mean difference in outcome observed for an active day when compared with a sedentary day. Additionally, we adjusted for the participant’s biological sex, self-reported race or ethnicity, age at onset, insurance type, pump start, study cohort, segmented study time (months), number of education modules completed (0–4), and a term to represent the interaction between study time and number of education modules completed. Pump start was coded as a time-varying covariate that starts at 0 and becomes 1 when the participant starts on an insulin pump. Study time was segmented at 4 months to accommodate new onset glycemic trends.
To address the potential impact of the number of education modules completed, an interaction term between study time and number of education modules completed was included in the model. While the model assumes different intercepts for the delivery of exercise education modules (assumed to have a linear effect), our main interest is in the monthly change in TIR, TAR, and TBR associated with the number of education modules completed after 4 months in the study. Statistical tests were two-sided and conducted at the 0.05 level of significance. All analyses were conducted in the R statistical computing framework, version 4.4.1 (R Core Team, Vienna, Austria).
Data and Resource Availability
The data sets include information that is protected health information; as it currently sits, it can lead to the identification of potential participants. Thus, the current institutional review board coverage for this study does not allow data sharing. However, the authors are willing to share nonprivileged data on a case-by-case basis as appropriate and indicated. Per the National Institutes of Health (NIH) guidelines, deidentified data sets will be made available on completion of all phases of the study, which we anticipate occurring in mid-2026. Please address any data requests to dessi@stanford.edu. Data requests will be reviewed per National Institute of Diabetes and Digestive and Kidney Diseases guidelines and timelines.
Results
A total of 144 eligible youth were approached for the 4T Exercise Program, of whom 116 consented to participate (Supplementary Fig. 1). Of the eligible youth who were consented (n = 116), 1 was deemed ineligible due to an incorrect diagnosis of T1D (n = 107 English speaking and n = 8 Spanish speaking), with 81 consenting to exercise education and a physical activity tracker as well as 34 consenting to a physical activity tracker only. Education modules were completed by parents and youth with T1D as follows: 67 parents and 69 youth (of 81) completed module 1; 59 parents and 59 youth completed module 2; 56 parents and 55 youth completed module 3; and 55 parents and 54 youth completed module 4 (Supplementary Fig. 1). Reasons for not completing the 4T Exercise Program included withdrawal (n = 6), opting out of the physical activity tracker portion and/or exercise education (n = 15), or lost to follow-up (n = 6).
Overall, 98 youth (85%) with T1D had completed the 4T Exercise Program at the time of analysis. Of those, 90 participants had at least 8 h of activity data between 6:00 a.m. and 9:59 p.m. and were included in the analysis for daily MVPA and step count. In the acute 24 h following an exercise or sedentary day, 77 participants had at least one matched exercise and sedentary day and were included in the analysis.
The median (IQR) age at the time of diagnosis was 13 (12–15) years, 45% were female, 44% were non-Hispanic White, 63% were on private insurance, and 92% were English-speaking. The mean ± SD HbA1c at diagnosis was 12.1 ± 2.7% (109 ± 6 mmol/mol) (Table 1). The median (IQR) time to CGM initiation was 10 (6–18) days after diagnosis, and insulin pump initiation was 132 (64–199) days after diagnosis. The overall demographics between 4T Exercise Program study 1 and study 2 participants were similar and, therefore, were combined in Table 1.
Table 1.
Participant demographics of combined 4T Exercise Program study 1 and completed study 2 data
| Characteristic | n (out of 98) |
|---|---|
| Age (years) at T1D diagnosis, median (IQR) | 13 (12–15) |
| Sex, n (%) | |
| Female | 44 (44.9) |
| Male | 54 (55.1) |
| Race or ethnicity, n (%) | |
| Asian or Pacific Islander | 9 (9.2) |
| Hispanic | 41 (41.8) |
| Non-Hispanic White | 43 (43.9) |
| Other | 5 (5.1) |
| DKA at diagnosis, n (%) | 58 (59.2) |
| HbA1c (%; mmol/mol) at diagnosis, mean (SD) | 12.1 (2.7); 109 (6.0) |
| Insurance type, n (%) | |
| Private | 62 (63.3) |
| Public | 36 (36.7) |
| Primary language, n (%) | |
| English | 90 (91.8) |
| Non-English | 8 (8.2) |
| Initiated CGM ≤30 days, n (%) | 97 (99.0) |
| Days to physical activity tracker initiation, median (IQR) | 31 (19, 38) |
| Days to CGM initiation, median (IQR) | 10 (6–18) |
| Insulin pump use within 1 year, n (%) | 58 (59.2) |
| Open loop, n (%) | 13 (13.3) |
| Hybrid closed loop, n (%) | 47 (48.0) |
| Days to pump initiation, median (IQR) | 132 (64–202) |
DKA, diabetic ketoacidosis.
The median (IQR) daily step count increased by 1,134 (445–1,519) steps per day from 1–3 months postdiagnosis to 10–12 months postdiagnosis (P < 0.001) (Fig. 1A). Similarly, the median daily MVPA increased by 11 (2–23) min per day from 1–3 months postdiagnosis to 10–12 months postdiagnosis (P < 0.001) (Fig. 1B).
Figure 1.
Overall summary of daily step count (A) and daily MVPA (B) across the first year of T1D diagnosis. Study periods are separated into quartiles including 1–3 months (green), 4–6 months (orange), 7–9 months (purple), and 10–12 months (pink) postdiagnosis. Box plots represent median and IQR; whiskers extend to ±1.5 IQR, and data points represent the spread beyond the upper limit.
The daily step count increased from a median (IQR) of 4,908 (2,245–7,953) at 1–3 months, to a median of 5,159 (2,152–8,620) at 4–6 months, 5,453 (2,369–8,644) at 7–9 months, and 6,042 (2,690–9,472) at 10–12 months postdiagnosis. Similarly, daily MVPA increased from a median (IQR) of 40 (20–74) min at 1–3 months, to a median of 45 (21–85) min at 4–6 months, 47 (23–85) min at 7–9 months, and 51 (22–97) min at 10–12 months postdiagnosis. Overall, there were no significant differences in daily step count and daily MVPA between youth wearing the activity tracker alone versus wearing the activity tracker and participating in education.
A total of 9,199 pairs of exercise versus sedentary days were included in the analysis. Exercise events were distributed relatively evenly throughout the day (Supplementary Fig. 2), with the median (IQR) time of the most prolonged exercise bout ending at 2:00 p.m. (11:00 a.m. to 5:00 p.m.). On average (±SD), each participant contributed to 23 ± 24 days classified as having short moderate-intensity activity, 69 ± 74 days of sustained moderate-intensity activity, and 35 ± 50 days of vigorous-intensity activity (Supplementary Table 1). Baseline CGM metrics in the 1 month prior to initiation in the 4T Exercise Program were 70 ± 16 %TIR, 28 ± 17 %TAR, and 1.8 ± 1.9 %TBR.
After controlling for participant and study characteristics, compared with sedentary days, days with at least 10 min of vigorous-intensity activity were associated with an increase in TIR of 2.3% (1.4–3.2%; P < 0.001), a decrease in TAR by 3.1% (2.2–4.0%; P < 0.001), and an increase in TBR by 0.8% (0.6–0.9%; P < 0.001) in the 24 h following activity (Fig. 2). Compared with sedentary days, days with a sustained duration of moderate-intensity activity (≥30 min) had no significant effect on TIR, a decrease in TAR by 0.80% (0.17–1.4%; P = 0.013), and an increase in TBR by 0.30% (0.20–0.41%; P < 0.001) in the 24 h following activity. Compared with sedentary days, days with a short duration of moderate-intensity activity (10–29 min) had no significant effect on TIR and TAR but had an increase in TBR by 0.21% (0.05–0.37%; P = 0.01) in the 24 h following activity.
Figure 2.
The 4T Exercise Program participants’ glucose TBR (<70 mg/dL), TIR (70–180 mg/dL), and TAR (>180 mg/dL) in the 24 h following exercise compared with sedentary days. A: Relative change data are reported as mean (95% CI) percent change in glucose TBR (red), TIR (green), and TAR (yellow), denoted by ◊ and colored bars. B: Absolute change data are reported as mean and 95% CI. The exercise categories are as follows: short moderate-intensity activity (10–29 min/day), sustained moderate-intensity activity (≥30 min/day), and vigorous-intensity activity (≥10 min/day).
With each education module completed, glucose TIR improved by 0.79% (0.67–0.90%; P < 0.001), such that, on average, completion of all four exercise education modules across the first year of diagnosis translates to an increase in TIR by 3.1% (2.7–3.6%) or 45 (39–52) min/day (Table 2). There were no significant differences based on sex, age, self-reported race or ethnicity, or insurance status.
Table 2.
4T Exercise Program participants’ glucose TBR (<70 mg/dL), TIR (70–180 mg/dL), and TAR (>180 mg/dL) in the 24 h following exercise compared with sedentary days
| Characteristic | TBR | TIR | TAR | |||
|---|---|---|---|---|---|---|
| β (95% CI) | P value | β (95% CI) | P value | β (95% CI) | P value | |
| Daily activity level | ||||||
| Sedentary day | — | — | — | |||
| Short-duration moderate intensity (10–29 min) | 0.21 (0.05 to 0.37) | 0.010 | −0.09 (−1.0 to 0.85) | 0.85 | −0.12 (−1.1 to 0.85) | 0.81 |
| Sustained moderate intensity (≥30 min) | 0.30 (0.20 to 0.41) | <0.001 | 0.50 (−0.12 to 1.1) | 0.11 | −0.80 (−1.4 to −0.17) | 0.013 |
| Vigorous intensity (≥10 min) | 0.79 (0.64 to 0.93) | <0.001 | 2.3 (1.4 to 3.2) | <0.001 | −3.1 (−4.0 to −2.2) | <0.001 |
| Study time (1–4 months) | −0.11 (−0.16 to −0.06) | <0.001 | −1.3 (−1.6 to −1.0) | <0.001 | 1.4 (1.1 to 1.7) | <0.001 |
| Study time (5–12 months) | 0.14 (0.08 to 0.20) | <0.001 | −2.2 (−2.6 to −1.9) | <0.001 | 2.1 (1.7 to 2.5) | <0.001 |
| Exercise education level | −0.09 (−0.18 to 0.00) | 0.050 | −2.9 (−3.4 to −2.3) | <0.001 | 2.9 (2.4 to 3.5) | <0.001 |
| Interaction of study time (5–12 months) and exercise education level | −0.04 (−0.05 to −0.02) | <0.001 | 0.79 (0.67 to 0.90) | <0.001 | −0.75 (−0.87 to −0.63) | <0.001 |
| Pump start | −0.17 (−0.33 to −0.01) | 0.032 | 2.1 (1.2 to 3.0) | <0.001 | −1.9 (−2.8 to −0.95) | <0.001 |
| Sex | ||||||
| Female | — | — | — | |||
| Male | −0.60 (−1.3 to 0.14) | 0.11 | 1.6 (−6.2 to 9.4) | 0.68 | −1.0 (−8.9 to 6.9) | 0.79 |
| Age (years) at T1D onset | −0.04 (−0.21 to 0.14) | 0.68 | 0.53 (−1.3 to 2.4) | 0.57 | −0.49 (−2.4 to 1.4) | 0.61 |
| Race or ethnicity | ||||||
| Non-Hispanic White | — | — | — | |||
| Asian, Pacific Islander, or other | −0.22 (−1.3 to 0.85) | 0.69 | −6.8 (−18 to 4.6) | 0.24 | 7.0 (−4.4 to 18) | 0.22 |
| Hispanic | −0.68 (−1.5 to 0.15) | 0.11 | 2.0 (−6.9 to 11) | 0.66 | −1.3 (−10 to 7.7) | 0.78 |
| Insurance type | ||||||
| Private | — | — | — | |||
| Public | 0.43 (−0.40 to 1.3) | 0.30 | −7.8 (−17 to 0.95) | 0.080 | 7.4 (−1.5 to 16) | 0.10 |
| Study cohort | ||||||
| 1 | — | — | — | |||
| 2 | −0.45 (−1.2 to 0.30) | 0.23 | 2.1 (−5.8 to 9.9) | 0.60 | −1.6 (−9.6 to 6.3) | 0.68 |
Negative education main effect indicates that, at baseline, youth who attend education have lower TIR and higher TAR; however, each education module completed contributes to an incremental increase in TIR of 0.79%, a decrease in TAR of 0.75%, and a decrease in TBR of 0.04%.
Supplementary Figure 3 reports HbA1c trajectories in the first 12 months of the 4T Exercise Program for participants who wore the activity tracker alone versus exercise education and activity tracker; the locally estimated scatterplot smoothing HbA1c values at 12 months postdiagnosis were 7.9 ± 0.9% and 7.5 ± 0.4%, respectively.
Conclusions
The 4T Exercise Program demonstrated that days with at least 10 min of vigorous-intensity physical activity compared with sedentary days led to significant improvements in daily TIR, along with lower TAR, and TBR that remained within clinical target recommendations (i.e., <4% TBR) in the 24 h after activity (12). Of note, physical activity levels did not vary whether participants wore an activity tracker alone or did education plus an activity tracker. The amount of education received (up to four modules) impacted CGM outcomes. We show that each structured exercise education session was associated with a further 0.79% increase in TIR.
The short- and long-term health benefits of regular exercise in youth and adults with T1D are indisputable (17). However, a recent study reported that only 16% of youth achieved, on average, ≥60 min of MVPA per day (18). Similarly, adults with new-onset T1D also spend less time doing MVPA compared with their peers without diabetes (19). In our study, participants’ daily MVPA increased from a median (IQR) of 40 (20–74) min to 51 (22–97) min from 1–3 months to 10–12 months postdiagnosis. We found that 32% (16 of 50) of the study cohort with available MVPA data at 12 months achieved the minimum recommended number of MVPA minutes per day, according to guidelines (1).
Exercise can also lead to significant disruptions in glycemia, particularly nocturnal hypoglycemia being more prevalent when average exercise is ≥60 min/day in youth with T1D (20). Unsurprisingly, fear of hypoglycemia remains one of the leading barriers to exercise in youth and adults with T1D (3,4,8,21). Educational and behavioral interventions for T1D demonstrate efficacy and improved clinical health outcomes (22–25), but discussion on the importance of implementing education early, particularly in the new-onset pediatric population, is lacking.
Health care providers have also mentioned limited time and knowledge and a need for standardization of exercise education for people with T1D (3,8,25). As such, our focus was to develop the initial education content with the goal of sharing these resources with other clinics nationally and internationally for broader implementation and scaling. We propose that exercise education should be provided by health care providers to all youth with T1D and their families shortly after diagnosis. In a previous paper (10), we demonstrated the feasibility and acceptability of initiating a structured exercise education program during new-onset T1D. Participants appreciated the hands-on tools and practical strategies provided for managing blood glucose levels around exercise, which empowered them to reengage in sports and daily physical activities with greater confidence (10). By pairing exercise education with early initiation of CGM, youth felt better equipped to manage glycemic fluctuations, enabling a smoother transition back to regular activities, including organized sports and physical education class at school. Parents also reported a greater sense of reassurance as they gained confidence in their child’s ability to prevent and address hypoglycemia (10). It is worth noting that, in this study, as increasing volumes and intensities of physical activity contributed to improved TIR metrics, exercise education provided an additive benefit to TIR across the first year of diabetes diagnosis. While we acknowledge that improvements in TIR metrics on physically active days as compared with sedentary days are modest, and, similar to previous findings in adults with T1D (26), we speculate that these improvements may be a combination of the volume and intensity of physical activity and exercise education. Taken together, although participants increased overall daily physical activity throughout the study, future studies may need to assess an exercise education program that focuses on encouraging increased physical activity to help youth with T1D meet recommended exercise guidelines.
A major strength is the novelty of the systematic, evidence-based (5,27,28), and structured, as well as virtual module-based, exercise education program that was designed to help educate youth with T1D and their families on how to exercise safely using diabetes-related technologies like CGM, a physical activity tracker, and insulin dose adjustments. Although the 4T Exercise Program model was delivered by an exercise physiologist, the content has been iterated on through feedback from the clinical care team and families in the 4T Exercise Program and is currently being delivered as standard of care by Certified Diabetes Care and Education Specialists in our clinic. In addition, the 4T Exercise Program targeted an understudied population of youth with new-onset T1D within ∼1 month after diagnosis.
Limitations for this study should also be acknowledged. This was an observational study, and participants were not randomized to different activity types or volumes. In addition, because of logistical limitations related to self-report data and infrequent clinic visits, we did not collect data on body mass changes over time or on dietary intake patterns, which can also influence glycemic outcomes (29,30). It is worth noting that a large part of the data collection period was during the coronavirus disease 2019 pandemic starting in March 2020, when telehealth visits began and the collection of these data were unreliable. It is also important to acknowledge that study participation was optional, and not randomized, and that comparisons of outcomes could not be made to a more appropriate control group. Nonetheless, some of the key comparisons that were made in this study, such as the effect of the amount and intensity of activity on CGM metrics, were within the cohort, rather than to a comparator group where the exercise programming was randomized to different volumes and/or intensities. Moreover, the top reasons youth did not opt in for the 4T Exercise Program included 1) did not want to wear a watch, 2) feeling overwhelmed with diabetes diagnosis at the time of approach, or 3) too busy. Since standards of care recommend regular exercise for all individuals with T1D (28), we did not believe clinical equipoise existed to do a randomized controlled trial of the structured exercise education program. While the current study design does not randomize participants to receiving education or an activity tracker, potential confounders were included in our models. Specifically, for the key glycemic metrics we report here (TIR, TAR, and TBR), we controlled for the time since diagnosis (and consequentially, time in the 4T Exercise Program), insulin pump initiation, and completion of exercise education sessions. Future studies could incorporate microrandomization to exercise education to determine whether there is an impact on the frequency and quantity of education delivered among different cohorts.
In summary, these findings demonstrate that days with as little as 10 min of vigorous-intensity activity led to significant increases in TIR, lower TAR, and TBR within clinical target recommendations in the 24 h postexercise. We also found that each exercise education session attended was associated with improved glycemic outcomes in the first year of diabetes diagnosis. Future studies should consider implementing an exercise education program that focuses on increasing physical activity levels, with a goal to help more youth with T1D meet exercise guidelines and improve health outcomes.
This article contains supplementary material online at https://doi.org/10.2337/figshare.29270858.
Article Information
Acknowledgments. The authors thank all of the youth with T1D and their families who participated in the 4T Exercise Program. We also thank the other members of the research team, including the clinical research coordinators, clinical staff, students in the Systems Utilization for Stanford Medicine group, the Quantitative Sciences Unit, and the T1D Working Group in Statistics and Informatics at Stanford Medicine Children’s Health. The authors especially thank all Stanford University or Stanford Children's Health staff and team members who are involved in the 4T Study, including K. Hood, D. Scheinker, R. Johari, A. Cortes, I. Balistreri, A., Loyola, R. Tam, E. Frank, J. Leverenz, A. Martinez-Singh, B. Conrad, A. Chmielewski, S. Lin, K. Clash, J. Senaldi, M.L. Horton, Lee, D. Naranjo, M. Tanenbaum, E. Fox, C. Guestrin, E. Hodgeson, K. Seeley, G. Kim, P. Dupenloup, P.A. Laforcade, V. Ding, B. Shaw, B. Bunning, B. Zou, A. Wang, Y. Jeong, Y. Chen, J. Kurtzig, N. Pageler, S. Ghuman, B. Watkins, G. Loving, and M. Clements from Children's Mercy Kansas City.
Funders had no role in the design of the study; in the collection, handling, analysis or interpretation of data; or in the decision to submit the protocol manuscript for publication.
Duality of Interest. D.P.Z. has received honoraria for speaking engagements from DexCom, Inc. and the American Diabetes Association, serves on the advisory board of the Diabetes Research Hub, and is a board member on the Breakthrough T1D NorCal Chapter. M.C.R. serves on the advisory panels of Zealand Pharma A/S, Zucara Therapeutics, and Indigo Diabetes; acts as a consultant for the Jaeb Center for Health Research; and has given lectures sponsored by DexCom, Inc., Novo Nordisk, and Sanofi. He is also a shareholder, or holds stocks in, Supersapiens and Zucara Therapeutics. A.A. has received research support from the Maternal Child Health Research Institute and grants K12DK122550 (Stanford University) and K23DK131342 from the National Institute of Diabetes and Digestive and Kidney Diseases during the conduct of the study. M.D. has reported receiving grants from NIH during the conduct of the study. D.M.M. has had research support from NIH and National Science Foundation, and his institution has had research support from DexCom, Inc., and he has consulted for Abbott, the Leona M. and Harry B. Helmsley Charitable Trust, Lifescan, Sanofi, Medtronic, Provention Bio, Kriya, and Bayer. P.P. serves as a consultant for Sanofi. No other potential conflicts of interest relevant to this article were reported.
Author Contributions. D.P.Z. and D.M.M. contributed to the conceptualization of the study. D.P.Z. and V.R. wrote the statistical analysis plan with oversight and input from M.D. V.R. was responsible for data curation and performed the formal analysis. D.P.Z. and D.M.M. acquired funding for this research study. D.P.Z. was responsible for the investigation, methodology, project administration, and writing of the original manuscript. All authors provided critical feedback and writing, comprising review and editing. D.P.Z. and V.R. were involved in validation of the study data. All authors contributed to manuscript revisions and approved the final submitted manuscript. D.P.Z. is the guarantor of this work and as such, had full access to the data in the study and takes responsibility for the integrity of the data and accuracy of the data analysis.
Prior Presentation. Preliminary study data were presented in part at the following conferences: the ISPAD 47th Annual Conference, virtual, 13–15 October 2021; the ISPAD 49th Annual Conference, 18–21 October 2023, Rotterdam, the Netherlands; the 83rd Scientific Sessions of the American Diabetes Association, San Diego, CA, 23–26 June 2023; and the 15th Advanced Technologies & Treatments for Diabetes Conference, Barcelona, Spain, 27–30 April 2022.
Handling Editors. The journal editors responsible for overseeing the review of the manuscript were Steven E. Kahn and Emily K. Sims.
Funding Statement
This study was funded by The Leona M. and Harry B. Helmsley Charitable Trust (G-2002-04251-2) and ISPAD-Breakthrough T1D Research Fellowship. This larger pragmatic 4T research study was also supported by National Institute of Diabetes and Digestive and Kidney Diseases grant R18DK122422 (D.M.M.) and by grant P30DK116074 via the Stanford Diabetes Research Center (1P30DK11607401). The 4T Study was also supported by Stanford’s Center for Clinical and Translational Education and Research award, under the Biostatistics, Epidemiology and Research Design Program UM1TR004921 (M.D.), and National Science Foundation 2205084 (D.M.M. and P.P.). The CGM supplies for the first month (one transmitter, three sensors, and one receiver per patient) were donated by Dexcom (D.M.M.). Funding for iOS devices and some CGM supplies was provided by a grant through the Lucile Packard Children’s Hospital Auxiliaries Endowment. The REDCap platform services at Stanford are subsidized by the Stanford School of Medicine Research Office and by grant UL1TR001085 from the NIH National Center for Research Resources and the National Center for Advancing Translational Sciences.
Footnotes
See accompanying article, p. 1719.
A list of members of the 4T Study Group can be found in the supplementary material online.
Contributor Information
Dessi P. Zaharieva, Email: dessi@stanford.edu.
4T Study Group:
Korey K. Hood, David Scheinker, Ramesh Johari, Diana Naranjo, Molly Tanenbaum, Emily Fox, Carlos Guestrin, Mark Clements, Ana Cortes, Ilenia Balistreri, Alondra Loyola, Rachel Tam, Eliana Frank, Jeannine Leverenz, Anji Martinez-Singh, Barry Conrad, Annette Chmielewski, Shannon Lin, Kim Clash, Julie Senaldi, Lauren Horton, Kylie Seeley, Mindy Lee, Gloria Kim, Paul Dupenloup, Pierre-Amaury Laforcade, Isha Thapa, Victoria Ding, Blake Shaw, Bryan Bunning, Johannes Ferstad, Jamie Kurtzig, Natalie Pageler, Simrat Ghuman, Brendan Watkins, and Glenn Loving
Supporting information
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