Night Owl Metabolism: Investigating the Impact of Chronotype on Glucose Metabolism in Youth
Phase: NA
Conditions: PreDiabetes, Overweight, Impaired Glucose Tolerance
Sponsor: Johns Hopkins University

 
Night Owl Metabolism
NCT06507722
1/30/2025

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
JHMIRB eFormA  01 
Version 4 Dated:   01/2021 
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JHM IRB - eForm A – Protocol 
 
 
• Use the section headings to write the JHM IRB eForm A, inserting the appropriate 
material in each. If a section is not applicable, leave heading in and insert N/A. 
• When submitting JHM IRB eForm A (new or revised), enter the date submitted to 
the field at the top of JHM IRB eForm A. 
 
******************************************************************************************** 
 
 
1. 
Abstract 
a. Provide no more than a one page research abstract briefly stating the problem, the 
research hypothesis, and the importance of the research. 
Adolescents commonly develop delayed sleep schedules in normal development 
related to physiologic processes, turning into “night owls” (late chronotype). Youth-onset 
type 2 diabetes (YoT2D) is a disorder with fast progression and early complications. 
Delayed sleep timing has been identified as a possible modifiable risk factor for YoT2D. 
Although prior studies have linked shifted sleep timing to impaired glucose metabolism, 
these studies may not extrapolate to youth with late chronotype as they utilize standard 
morning testing with oral glucose tolerance tests (OGTTs), at a time mis-aligned to the 
typical schedule of an individual with late chronotype. As glucose tolerance worsens as 
the day progresses until the middle of the night in healthy individuals, testing at a time 
when youth with late chronotype are typically asleep may alter results and lead to 
potential mis-diagnoses. The goal of this study is to investigate whether alignment of 
glucose metabolic testing with chronotype improves glycemic outcomes and whether 
alignment of first morning meal timing to chronotype improves post-prandial glycemic 
response in youth with late chronotype. The proposed study uses a novel and rigorous 
randomized cross-over study design in youth (18-23y) with late and non-late chronotype 
(n=35 per group) to assess the glycemic effect of “aligning” an OGTT or first-meal of 
day to a subject’s chronotype. Both groups will undergo 2 OGTTs (aligned and mis-
aligned with chronotype) to compare glucose tolerance and insulin sensitivity within-
subject (primary outcome) and between groups (Aim 1). Then, youth will also undergo 
two standardized meals (aligned and mis-aligned with chronotype) while wearing 
continuous glucose monitoring to compare postprandial glucose excursions within-
subject and between groups (Aim 2). A pilot Exploratory Aim 3 (n=12 per group) will 
investigate delayed melatonin patterns under dim-light as a potential pathophysiologic 
mechanism behind abnormal glucose tolerance in youth with late chronotype on 
morning OGTTs. This study has potential implications for both clinical and research 
practices, as well as meal timing recommendations.  
2. 
Objectives (include all primary and secondary objectives) 
This study has two main objectives with an additional exploratory third objective:  

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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Aim 1: To compare morning vs. midday glucose tolerance and insulin sensitivity (IS) 
(analyzed by OGTT Minimal Model) in youth with late chronotype (primary analysis) and 
non-late chronotype, using OGTT in a controlled lab setting. 
Aim 2: To compare morning vs. midday first-meal of day standardized mixed meal 
glycemic responses in youth with late chronotype (primary analysis) and non-late 
chronotype, using continuous glucose monitor (CGM) in a real-world setting. 
Exploratory Aim 3: To examine a possible role of melatonin in misalignment-induced 
glucose intolerance. 
3. 
Background (briefly describe pre-clinical and clinical data, current experience with 
procedures, drug or device, and any other relevant information to justify the research) 
The proposed study is based on preliminary data from 2 years of research funded by an 
Administrative Supplement on NIDDK R01DK115648, “Cardiometabolic Health in 
Adolescents of South Asian Ancestry- the CHAriSmA study” (PI: Dr. Sheela Magge). 
The parent R01 compares cardiovascular risk factors (including using OGTT and oral 
Minimal Model) between South Asian, African American, and White adolescents aged 
12-21y. A subset of the parent study participants measured 15d of actigraphy along with 
sleep diaries (text-messaged twice daily) in order to examine the cross-sectional 
relationships between glucose metabolism with sleep duration and sleep timing. In the 
43 participants analyzed (out of 63 participants recruited over the course of 21 months, 
an average 3 participants per month), the cohort was (median (IQR)): age 20.2y (18.6-
21.4), 49% female, BMI 25.8 kg/m2 (24.1-28.6), baseline HbA1c 5.0% (4.9-5.3). 
Actigraphy measures demonstrated (median (IQR)): normal young adult sleep duration 
7.5 hours (6.8-8.1), minimal social jetlag (difference between weekend and weekday 
sleep onset) 37.4 minutes (-13.4, 84.7), and delayed sleep onset 1:00AM (12:02AM-
1:48AM) with 21% after 2AM. When adjusting for BMI, participants with later sleep timing 
had significantly higher OGTT 2-h glucose (for every hour later in habitual sleep onset, 
2-hr glucose was 7.4 mg/dl higher), reduced IS (by 28.5% for each hour later in sleep 
onset), and higher insulin incremental area under the curve (iAUC). Based on these 
results, a 4-h difference in bedtime would equate to a clinically significant ~30 mg/dL 
difference in 2-h glucose on a morning OGTT. In addition, 8 (19%) research participants 
had impaired glucose tolerance (IGT), and youth diagnosed with IGT had later sleep 
onset than youth with normoglycemia. Each hour later of delayed sleep onset was 
associated with a 3.3x greater odds of being diagnosed with IGT. 
Sleep duration was not associated with any glycemic outcomes and all analyses 
remained significant when adjusting for obstructive sleep apnea (OSA) risk (screened 
using Berlin Questionnaire and Sleep-Related Breathing Disorder scale). We concluded 
that youth with late sleep timing had glucose intolerance and reduced IS on a morning 
OGTT (median (IQR) timing of OGTT: 9:34AM (9:18AM-9:49AM)). However, we do not 
know if this glucose intolerance would be resolved by aligning OGTT timing to 
chronotype or how this data corresponds to glucose ingestion in real world settings.  
Additional preliminary data pertinent to the proposed aims include a prior project 
evaluating the relationship between sleep duration with glycemic control by hemoglobin 
A1c (HbA1c) (primary analysis) and glycemic metrics by CGM (secondary analysis) in 
adolescents with youth-onset type 2 diabetes. This project provided me with skills in the 

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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use of actigraphy and CGM in clinical research and confirmed the commonality of late 
chronotype with delayed sleep onset (median (IQR): 1:40AM (12:22AM-2:32AM)) in an 
adolescent population (median (IQR) age 15.6y (14.2-17.5)). 
4. 
Study Procedures 
a. Study design, including the sequence and timing of study procedures (distinguish 
research procedures from those that are part of routine care). 
Overall Study Design: This project will use a randomly ordered paired 2-group cross-
over design. Aims 1 and 2 use complementary methods to assess in-lab (OGTT) (Aim 1) 
and real-world (CGM monitoring following a standardized meal) (Aim 2) glucose 
metabolism at different times of day. Three days are allotted at start of study to gather 
sleep data via actigraphy to assess normal routine patterns prior to the first OGTT. In 
Aim 1, all participants (total n=70, n=35 in each chronotype group) will wear actigraphy 
for sleep measures over an 11-day period and will be randomized to start with either late 
(12:30PM) or early (8:30AM) OGTT on Day 4 and then undergo the opposite timing on 
Day 11, allowing a 1-week washout period between OGTTs. After Aim 1 procedures, at 
least 1 week without procedures will be allowed for wash-out before beginning Aim 2. In 
Aim 2, participants will again wear actigraphy as well as CGM for real-world glucose 
monitoring for 8 days, and then will be randomized to start with either a late (12:30PM) 
or early (8:30AM) first-meal of day standardized meal shake on Day 1 and then have the 
opposite meal timing on Day 8 (with a 1-week washout period in between). After 
completion of Aims 1-2, a subset (total n=24, n=12 per chronotype group) will undergo 
Exploratory Aim 3, with dim-light melatonin measurements per published procedures in 
prior studies.  
            All procedures described are for research purposes only:  
1. Pre-screening Visit (Virtual): We will obtain a medical history, weight/height, and self-
reported sleep patterns as outlined by the telephone screening script. If the participant 
appears to be eligible, we will continue into the consent and screening visit process. If 
the participant is not eligible, they can give us permission to contact them at a later date 
if they become eligible.  
2. Screening Visit (Virtual): After obtaining informed consent, the participant will complete 2 
screening questionnaires to confirm eligibility: (1) one questionnaire to gather information 
on OSA risk(Berlin Questionnaire (validated in adults)). Those who screen high-risk for 
OSA or who have insufficient typical sleep duration (<7 hours) or excess social jetlag (>2 
hours) will be ineligible. (2) and an Alcohol Screening Questionnaire (2021 Youth Risk 
Behavior Survey). Those who screen as binge drinkers will be ineligible. Eligible 
participants will be mailed an actigraphy watch. Once the watch is received, the subject 
will be randomized and OGTT visits will be scheduled. 
3. Start of Aim 1 Visit, Day 0 (Virtual): We will plan this study visit during a time that is 
routine for the participant without holiday or vacation schedules within the subsequent 2 
weeks. During this visit, the study coordinator will review the study plan for Aim 1 with 
the participant including dates of visits, instructions for fasting prior to the OGTT (at least 
12-h the night prior to the test), and advise the subject to follow a typical carbohydrate 
diet (≥ 150g of carbohydrate per day) and a ≥ 50g meal the night before the test to avoid 

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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false positive results seen in prior studies. The study coordinator will instruct the 
participant to start wearing the actigraphy watch on their non-dominant wrist. The twice-
daily REDCap text-message based sleep diary will start the next morning. 
4. 
OGTT #1 Visit, Day 4 (In-Person): The first OGTT for each participant will occur on Day 
4. All participants from both chronotype groups will be randomized to receive the Early 
(8:30AM) or Late (12:30PM) OGTT first. . At placement of blood-drawing IV, a HbA1c 
level will be drawn. OGTT will start with an oral glucose load (1.75 g/kg; max of 75 g) 
ingested over 2 minutes (at time = 0) and will last 2-h with 8 samples drawn at timepoints 
(min: -10, 0, 10, 20, 30, 60, 90, 120) for measurement of glucose, insulin, and c-peptide. 
At each timepoint, glucose will be measured via a glucometer. If fasting or 2-h glucose is 
in IGT or diabetes range, blood will be sent for real-time laboratory confirmation of 
glucose during the OGTT. At the visit, we will also conduct anthropometrics 
measurements and questionnaires to gather chronotype and social jetlag (Munich 
chronotype and Morningness-Eveningness Questionnaire), family history, medical 
history, birth history, and medication list. 
5. OGTT #2 Visit, Day 11 (In-Person): The second OGTT will occur on Day 11 of the study 
to allow for a washout period of 7d between OGTTs. All participants will perform the 
OGTT that they did not previously perform (Early - 8:30AM or Late - 12:30PM). At the 
end of the OGTT, participant will remove and return actigraphy watch.  
6. CGM Visit, Start of Aim 2, ≥ 1 week and < 4 weeks after OGTT #2 visit (In-Person): We 
will plan this visit during a routine time for the participant without holiday or vacation 
within the subsequent week. Participants will come in to be provided a second 
actigraphy watch, a CGM sensor, and standardized meal shakes. The placement of 
CGM will be done with the participant by research team. Participants will be instructed to 
eat and sleep on their typical patterns during this time except for days of standardized 
meals. During this visit, the study coordinator will review the Aim 2 study plan with the 
participant including dates and times of standardized meal timing and advise the 
participant to fast for 12-h prior to the scheduled time of the standardized meal. The 
participant will be instructed to start wearing the actigraphy watch on their nondominant 
wrist and will be assisted virtually in inserting the CGM sensor. The twice-daily text-
message based sleep diary will initiate with 1st sleep diary sent on the following morning.  
7. Standardized Meals (no visit): Participants will be given Boost Plus meal-replacement 
shakes at the CGM visit. During Aim 2, standardized meals will be ingested as first-meal 
of day (fasting until meal) on Day 1 and Day 8. Participants will be asked to consume 
their meals within 10 minutes and limit their physical activity during the 8-h prior to the 
meal and the 3-h following the meal. 
8. Dim-light Melatonin Measurement Visit (In-Person): A subset of participants (n = 12 per 
chronotype group) will be admitted to a dimly lit (<4 lux), temperature-controlled room 
and will undergo dim-light melatonin onset (DLMOn) and dim-light melatonin offset 
(DLMOff) assessment using salivary collection per published procedures. The saliva 
collection will begin at least 6-8h before habitual bedtime and continues at 30-minute 
intervals until 2h after habitual bedtime at which point participants will be allowed to 
sleep. DLMOn will subsequently be calculated as the interpolated time point at which 
melatonin concentrations cross and maintain above 3 pg/mL, rounded to the nearest 
half-hour. Participants will be awakened and melatonin measurement will re-start at 2h 
before habitual wake-up with 30-minute interval saliva sampling. DLMOff will be defined 

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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as the linear interpolated time point at which melatonin concentrations cross and 
maintain below 3 pg/mL. 
Procedures Ongoing during Aims 1 and 2: 
1. Actigraphy (Aim 1 Day 0-11, Aim 2 Day 0-8): The ActiGraph GT3XP-BTLE 4GB Activity 
Monitor, a watch-like device, is a research-grade triaxial accelerometer, that reliably 
measures duration, onset and offset of sleep. Participants will be asked to wear the 
ActiGraph watch on their non-dominant wrist twice: first, for 11 days and nights starting 
at the Day 0 virtual visit and ending at the 2nd OGTT, and then replaced at the start of 
Aim 2 and mailed back in a provided pre-paid USPS box.  
2. CGM Monitoring (Aim 2 Day 0-8): A CGM sensor (Dexcom G6 Professional CGM) will be 
placed in-person on the participant’s abdomen on Start of Aim 2 In-person  The process 
of CGM placement will be reviewed in person at CGM visit. Participants will wear the 
CGM for 8 days (blinded) during Aim 2, and then will return it via a provided pre-paid 
USPS box. The CGM collects glucose data every 5min.  
3. Text-Message Based Sleep Diary: A sleep diary will be sent via text-message twice daily 
to all participants during both Aim 1 and Aim 2. Questions include self-reported timing of 
sleep, sleep latency, awakenings, sleep quality, and periods of actigraphy non-wear to 
aid in actigraphy analysis. Questions also assess caffeine intake, use of sleep aids, 
screen time use, irregular schedules, meal timings, snack timing, alcohol intake, and 
exercise. 
b. If your study involves data/biospecimens from participants enrolled under other 
research studies with a written consent or under a waiver of consent, please list the 
IRB application numbers for those studies. n/a 
c. Study duration and number of study visits required of research participants. 
Participants will be enrolled in the study until all procedures have been completed 
(up to 3 months if participating in all aims (including Aim 3 DLMOn/DLMOff), up to 2 
months if only participating in Aims 1 & 2). Participation in Aims 1 & 2 involves 1 
screening visit (virtual), 1 virtual visit, and 3 in-person visits. Participation in Aim 3 
involves an additional overnight in-person visit.  
d. Blinding, including justification for blinding or not blinding the trial, if applicable. 
For randomization in Aim 1, participants will be assigned to Early or Late OGTT for 
the first visit with crossover to the alternate for the second visit (Fig 1). 
Randomization will be done via a computer-generated random number list prepared 
by the statistician who will have no clinical involvement in the study. The list will then 
be provided to the study coordinator. The investigator will not be masked to 
assignment for Aim 1 as they will be available during OGTT testing as needed. In 
Aim 2, participants will be assigned to Early or Late standardized first meal for Day 1 
with crossover to the alternate for Day 8. Randomization will be done via a computer-
generated random number list prepared by the statistician who will have no clinical 
involvement in the study. The list will then be provided to the study coordinator, and 
the investigator will be blinded to randomization 

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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e. Justification of why participants will not receive routine care or will have current 
therapy stopped. n/a 
f. Justification for inclusion of a placebo or non-treatment group. n/a 
g. Definition of treatment failure or participant removal criteria.  
Participants may be removed from the study if, in the opinion of the study team, 
continued participation would cause harm to the participant or if they fail to comply 
with study procedures.  
h. Description of what happens to participants receiving therapy when study ends or if a 
participant’s participation in the study ends prematurely. 
n/a 
i. If biological materials are involved, please describe all the experimental procedures 
and analyses in which they will be used. 
Blood collected during the OGTTs will be used to measure glucose, insulin, and c-
peptide, which will be used to calculate measures of glycemic control and variability. 
Fasting blood samples will also be used to measure hemoglobin A1c. If blood 
samples remain after these planned analyses, they will be stored for future research. 
Participants in Exploratory Aim 3 (DLMOn/DLMOff) will also generate saliva 
samples, which will be analyzed for salivary melatonin levels. These results will be 
used to calculate DLMOn and DLMOff times.  
5. 
Inclusion/Exclusion Criteria 
Inclusion Criteria:  
• 
Age 18-23 years 
• 
Overweight per adult CDC guidelines BMI: 25-30 
• 
Post-puberty per participant report  
• 
Normal sleep duration (average >7 hours per night), per participant report  
• 
Social jetlag < 2hours, per participant report 
Exclusion Criteria:  
• 
Known diabetes, sleep disorders, or pregnancy and/or known major organ 
system illness or genetic syndrome that can affect glucose metabolism or sleep  
• 
Medication use known to affect insulin sensitivity, glucose tolerance, or circadian 
rhythm  
• 
High risk for OSA, per questionnaire   
• 
Night shift work  
• 
Unable to read/write in English, as questionnaires are only validated in English  
• 
Unwilling or unable to provide informed consent or assent   
• 
History of eating disorder  
• 
Self-reported binge drinker  
• 
Pregnant or lactating female  
• 
Parent/guardian of child(ren) who may disrupt sleep  

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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• 
Participants who have travelled across time zones must have adequate time to 
recover from jet lag prior to enrollment (i.e., at least 3 days per time zone). Travel 
across >1 time zone after enrollment in the study will not be permitted. 
6. 
Drugs/ Substances/ Devices 
a. The rationale for choosing the drug and dose or for choosing the device to be used. 
b. Justification and safety information if FDA approved drugs will be administered for 
non-FDA approved indications or if doses or routes of administration or participant 
populations are changed. 
c. Justification and safety information if non-FDA approved drugs without an IND will 
be administered.  
Dexcom G6 Pro Continuous Glucose Monitors: Continuous glucose monitors (CGMs) 
are minimally invasive, single-use devices that are applied to the skin and continuously 
measure interstitial glucose for up to 10 days, thereby potentially revealing more 
dysglycemia than a time point (OGTT) or average (hemoglobin A1c). CGMs are 
approved for use by people with diabetes to monitor trends in glucose and make real-
time decisions about diabetes management. Professional CGMs are also approved to 
assess glycemic variability in the home environment in individuals over age 2 without 
diagnosed diabetes. The Dexcom G6 Pro CGMs will be used in blinded mode, so 
participants will not be able to see their glucose measurements.  
ActiGraph wGT3X-BT: The ActiGraph wGT3X-BT is a research-grade FDA-cleared tri-
axial accelerometer used to measure activity. When used in combination with ActiGraph 
algorithms, the data can be used to estimate sleep timing and duration. Participants will 
be blinded to actigraphy results.  
7. 
Study Statistics 
a. Primary outcome variable. 
The primary outcome variables for each study aim are listed below:  
Aim 1: Within-subject difference in 2-h glucose between Early and Late OGTT in late 
chronotype group 
Aim 2: Within-subject difference in 2-h post-prandial incremental area under the 
curve of glucose between Early and Late Meal in late chronotype group 
Exploratory Aim 3: Relationship between DLMOff and morning OGTT 2-h glucose 
and insulin sensitivity 
b. Secondary outcome variables. 
Secondary outcome variables for each study aim are listed below:  
Aim 1:  
§ 
Within-subject difference in insulin sensitivity between Early and Late OGTT 
in late chronotype group 

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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Version 4 Dated:   01/2021 
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§ 
Within-subject difference in insulin secretion indices between Early and Late 
OGTT in late chronotype group 
§ 
Within-subject difference in fasting glucose between Early and Late OGTT in 
late chronotype group 
§ 
Within-subject difference in incremental area under the curve of insulin 
between Early and Late OGTT in late chronotype group 
§ 
Within-subject difference in disposition index between Early and Late OGTT 
in late chronotype group 
§ 
Within-subject difference in insulin clearance between Early and Late OGTT 
in late chronotype group 
§ 
Between-group differences in all above primary and secondary outcome 
variables as well as HbA1c 
 
Aim 2:  
§ 
Within-subject difference in 2-hour post-prandial peak between Early and 
Late Meal in late chronotype group 
§ 
Comparison between chronotype groups of all primary and secondary 
outcome variables as well as mean glucose, percent time spent above 120 
mg/dL, percent time spent above 140 mg/dL, number of excursions greater 
than 140 mg/dL, standard deviation of glucose, and coefficient of variation of 
glucose 
 
Exploratory Aim 3:  
§ 
Relationship between melatonin level at 8:30 AM and morning OGTT 2-h 
glucose and insulin sensitivity 
§ 
Relationship between dim-light melatonin onset (DLMOn) and morning OGTT 
2-h glucose and insulin sensitivity 
§ 
Comparison between chronotype groups of DLMOff and morning melatonin 
level   
c. Statistical plan including sample size justification and interim data analysis. 
Statistical Plan for Primary Analysis in Aim 1: A unified approach based on mixed 
effects general linear modeling (meglm, STATA 17) will be pursued. This approach 
enables analysis to account for dependencies owing to use of “own controls” and to 
overcome the issue of outcomes that do not initially meet normality and 
homoscedasticity assumptions. Initially, meglm models separately applied to each 
chronotype group will include main and interactive effects of intervention and 
intervention order (early-late or late-early). The interaction effect will only be retained 
if it reaches statistical significance. For Aim 1, the primary analysis will evaluate the 
within-subject difference in the late chronotype group between Early OGTT and Late 
OGTT in 2-h glucose (primary outcome), IS, and other insulin secretion and 
clearance metrics. The above modelling approach will allow us to adjust variance 
estimates to account for the aforementioned dependencies in the data. 
Statistical Plan for Primary Analysis in Aim 2: For Aim 2, the primary analysis, will, as 
above, use a mixed effects general linear model comparable to Aim 1 to estimate in 
the late chronotype group the within-subject difference in 2-h iAUC of glucose 
(primary outcome) and post-prandial glucose peak between Early Meal and Late 

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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Meal. Similar models will be utilized for advanced comparisons of sleep and glycemic 
excursions (lme4 package, R).  
Aims 1 and 2 Secondary Analysis: Importantly, secondary analysis will examine 
differences between chronotype groups in Early vs. Late Meal and Early vs. Late 
OGTT testing in regard to Aim 1 and 2 outcomes. These analyses will control for 
differences in age, sex, BMI, race/ethnicity, sleep duration, and work/education 
status, and sensitivity analyses will also be stratified by sex. Should use of integrated 
transformations, through link functions, fail to meet model assumptions, analysis can 
shift to comparing median levels to relax assumptions. 
Statistical Plan for Aim 3: Regression modeling will be used to evaluate evidence in 
pooled group comparisons that DLMOff predicts 2-h glucose and IS on Early OGTT. 
Secondary analysis will evaluate the association between melatonin level at 8:30AM 
(timing of Early OGTT) and DLMOn with OGTT outcomes. Pooling data from both 
aligned and mis-aligned participants will evaluate the full spectrum of the relationship 
between circadian metrics and morning glucose responses. DLMOff will be 
compared between groups by T-test or equivalent. 
Sample size and Power Calculations: G*Power was used to develop sample size 
estimates to detect clinically meaningful effect size differences. Based on a 2-tailed 
type 1 error of 0.05 in own-control comparisons, a sample size of n=35 per 
chronotype group (total n=70) provides >90% power to detect effect size difference 
of 0.6 between paired means. A sample size of 35 per group was also determined to 
have 80% power to detect a 0.65 effect size difference in independent, between-
group comparisons assuming a 1-tailed test and type 1 error of 5%. Based on these 
estimates, the study is adequately powered to detect clinically meaningful effects for 
study aims and hypotheses. In Exploratory Aim 3, a sample size of n=24 will allow 
the study to estimate the strength of relationship as r2 +- 95% CI between 2-h 
glucose or IS and DLMOff. It will demonstrate feasibility to measure and the potential 
relationship between circadian metrics and metabolic outcomes to support future 
hypotheses. 
d. Early stopping rules. 
If the Hopkins/Affiliates faculty/staff member designated to periodically review 
adverse events raises concern for need to stop early, then study investigators will 
review available data and make decision regarding stopping early. 
8. 
Risks 
a. Medical risks, listing all procedures, their major and minor risks and expected 
frequency.  
b. Steps taken to minimize the risks. 
c. Plan for reporting unanticipated problems or study deviations. 
d. Legal risks such as the risks that would be associated with breach of confidentiality. 
e. Financial risks to the participants. 
Questionnaires, Health History and Anthropometric Measures: These procedures 
acquire information that is routinely collected in the process of medical care of patients. 
There are not any significant physical risks from these procedures. As with all medical 

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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information, there is always the risk of psychological distress if personal health 
information is not held confidential within the wishes of the participant. 
Phlebotomy & multiple blood sampling: The blood volume collected during OGTT will be 
approximately 75 mL with an additional 25 mL for other fasting labs, totaling 100 mL per 
OGTT and 200 mL in total. The blood volume removal is much less than the maximum 
blood volume removal per 8-week period recommended by OHRP (Adults < 10.5 mL/kg 
or 550 ml, children < 7mL/kg).  
There is a risk of bruising and discomfort at the venipuncture site. Blood draw may result 
in temporary discomfort from needle stick, bruising, fainting, weakness, and rarely an 
infection at the site. These risks of complication will be mitigated with standard sterile 
technique and staff experienced performing phlebotomy. 
OGTT: Beyond the blood sampling concerns described above, the risks for OGTT 
include temporary high or low blood sugar and upset stomach.  
The OGTT is frequently used to screen for diabetes and impairments in glucose 
regulation in children both within the confines of a study and in routine clinical practice; 
additional intermediate blood draws will be performed for glucose, insulin and c-peptide 
in order to assess insulin sensitivity.  Because of these intermediate time points for blood 
collection, an intravenous line will be placed, which can be associated with discomfort 
and a small risk of infection. Experienced research nurses will perform the OGTT in the 
Outpatient JHU ICTR facilities; OGTT are routinely performed in this setting.  Eight blood 
samples are required and the volumes of blood will be minimized to reduce the risk of 
anemia.  
There is a small and rare risk of an upset stomach when drinking the sugar drink. The 
participant will need to fast overnight prior to the OGTT which may cause an upset 
stomach, a headache, or light-headedness. These symptoms are occasional but not 
serious. The major risk of the oral glucose tolerance test is hypoglycemia. Hypoglycemia 
is reported in 20-25% of otherwise healthy individuals who undergo oral glucose 
tolerance testing. Subjects will be closely monitored during studies by personnel with 
experience in managing hypoglycemia and its associated problems. Portable glucose 
meters will be used to allow rapid detection and prompt treatment of hypoglycemia. 
Plasma glucose levels will be measured at the scheduled intervals. In addition, blood 
glucose levels will be measured (from blood drawing IV or by fingerstick) at any time 
during the study if symptoms of hypoglycemia occur (such as tremors, sweating, and 
irritability). Subjects will be treated with oral glucose supplementation (e.g. orange juice) 
if symptomatic.  Blood glucose will be monitored until normalization is assured.   
 
CGM: CGM use has a low risk of causing skin irritation, bruising, or infection. 
Participants will be advised to use standard sterile technique when the CGM is placed 
(during the start of Aim 2 virtual visit). If a participant has an adverse reaction in the form 
of irritation, infection or discomfort at the CGM insertion site, the study investigator will 
evaluate and manage the reaction. A CGM provides a continuous reading of blood 
sugars 24 hours a day, which can feel like a lot of information. In order to minimize 
anxiety in this population of overweight young adults, participants will be blinded to the 
readings, and the data will be downloaded by the study team after the period of wear. 
 
Standardized Meal: The meal timing intervention (differing first-morning of day meal 
time) poses minimal risk. Potential adverse effect of the intervention may include 
participants’ dislike of the food provided. 

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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Version 4 Dated:   01/2021 
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ActiGraph: Risks associated with ActiGraph use are minimal, and mainly consist of risk 
of skin irritation from the band of the device. Watch bands will be sanitized between 
uses, and participants will be advised to remove the device in the event of skin irritation. 
Participants will be blinded to all actigraphy data and may also find it inconvenient or 
uncomfortable to wear the activity monitor on their wrist. 
DLMOn/DLMOff: Like any sleep study, the DLMOn/DLMOff procedure may result in 
sleep that is less restful than a participant’s typical at-home sleep, due to discomfort in 
the lab environment and monitoring equipment. Only a subset of study participants will 
undergo DLMO/DLMOff, and those who elect to participate may terminate their 
participation at any time. 
Legal risks, including loss of confidentiality, will be mitigated with use of unique study 
identifiers, IRB-approved staff, locking up paper records and utilization of Johns Hopkins 
approved servers for data containing protected health information. Any publications 
derived from study will not identify subjects in any way. However, participation in 
research may lead to unintentional loss of privacy. 
Financial Risks: There are no anticipated financial risks to participants.  
9. 
Benefits 
a. 
Description of the probable benefits for the participant and for society. 
There is no direct benefit to the participants, but the findings from this study may help 
others in the future 
10. 
Payment and Remuneration 
a. 
Detail compensation for participants including possible total compensation, 
proposed bonus, and any proposed reductions or penalties for not completing the 
protocol. 
Participants may earn up to $1,050 if they complete all study procedures including Aim 
3, or up to $550 for completing only Aims 1 & 2, according to the schedule outlined 
below:  

 
Date: 1/30/2025 
Principal Investigator: Talia Hitt, MD MPH MSHP 
Application Number: IRB00428863 
 
 
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Version 4 Dated:   01/2021 
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Compensation is sufficient to cover the costs of parking. 
11. 
 
a. 
Detail costs of study procedure(s) or drug (s) or substance(s) to participants and 
identify who will pay for them. 
The cost of all study procedures and devices will be paid for by the study.  
12. 
Transfer of Materials 
Transfer of biospecimens from Johns Hopkins to another organization for research 
purposes and receipt of biospecimens from an outside organization for your research 
must adhere to JHU policies for material transfer (https://ventures.jhu.edu/faculty-
inventors/forms-policies/ ) and biospecimen transfer 
(https://hpo.johnshopkins.edu/enterprise/policies/176/39187/policy_39187.pdf?_=0.622
324232879). n/a 
Procedure
Compensation
Aim 1:
OGTT 1 Completion
$150
OGTT 2 Completion
$75
Watch Returned 
$25
Half of Data Present on Watch and Sleep Diary
$25
Additional Bonus for Full Data on Watch and Sleep Diary
$50
Maximum total for Aim 1
$325
Aim 2:
Placement of CGM Completion
$25
Watch Returned 
$50
CGM Returned
$50
Half of Data Present on Watch and Sleep Diary
$25
Half of Data on CGM
$25
Additional Bonus for Full Data on Watch/Sleep Diary/CGM
$50
Maximum total for Aim 2
$225
Aim 3 (substudy):
DLMOn/DLMOff
$500
Maximum total for Aim 3
$500
Maximum Compensation
$1,050