An observational study in Hypoglycemia and Cerebral Blood Flow, sponsored by Joslin Diabetes Center. Recruiting at 1 site in United States. Open to participants aged 18 Years to 70 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-11-28.
Sponsored by Joslin Diabetes Center · Observational
This is a pilot study (small-scale study) that aims to understand more about how blood flow changes in people who have low blood sugar after bariatric surgery (post-bariatric hypoglycemia) compared to those who have had surgery without hypoglycemia, those who have hypoglycemia without surgery, or those who do not experience low blood sugar.
This study has two phases. This is the first phase, and the purpose is to test comfort and feasibility of a novel in-ear wearable device (Lumia Health) that measures blood flow changes to the head. Information from the study will help the investigators determine if the device is suitable to be used in the second phase of the study.
Visit 1 (Screening) This visit will last about 2 hours. Participants will be asked to come to Joslin Diabetes Center.
During the screening visit, a study team member will go over the informed consent form with participants and will explain why this study is being done and the study procedures involved. Participants will have to sign the consent form before any study related procedures take place. After participants sign the consent, the following procedures will be done to ensure eligibility and that it is safe to be part of the study.
Questionnaires: Investigators will ask participants to fill out several questionnaires that will help the investigators assess any symptoms of low blood sugar or autonomic symptoms:
Procedure: (1) Removing earrings or jewelry if needed and cleaning the outer ear to ensure a secure fit. (2) Positioning the device on the frontal surface of the left ear cartilage. (3) Adjusting it to fit comfortably. If participant experiences any discomfort during placement, they will be asked to inform the study team.
Employees at Lumia Health will process signals from the device and provide the Joslin team with the blood flow information. This information will be de-identified, meaning it will not include any personally identifiable data.
Dexcom G6 Pro: This continuous glucose monitor (CGM) will be placed under the skin on the abdomen to monitor the participant's sensor glucose (sugar) levels.
Insertion Procedure: (1) A suitable location on the abdomen is identified. (2) The CGM is placed against the skin at the chosen site. The sensor is inserted in the skin with a simple press or click; this causes little to no discomfort. (3) A small transmitter is connected to the sensor to allow glucose readings to be transmitted to a monitoring device (receiver), which the participant will keep with them during the duration of the monitoring period.
Diaries: Investigators will ask participants to keep a written paper diary of daily meals, liquids (including caffeinated beverages), physical activity and any issues with the device (Lumia).
At the end of the visit, the participant will be scheduled for the next 2 visits. Additionally, the participant will be provided contact information for the study team in case any questions or issues arise during the study.
Visit 2 (Follow up)
This visit will happen remotely, between days 4-6 after Visit 1. A study team member will call the participant by video or phone. This visit will include:
Wellness check: The investigators will check how the participant is doing, see if there are any problems, and ask about experience with both the ear and CGM devices.
Ear device check: A member of the study team will review the data collected on the cloud from previous days to ensure the ear device is functioning properly. If everything is working well, the investigators will encourage participants to continue wearing the device . If there are issues with data collection or problems with device, the investigators will provide instructions to improve data collection and schedule a follow-up call if needed.
Questions and support: Investigators will be available to answer any questions that the participant may have.
At the end of this call visit, the investigators will provide instructions for the next visit.
Visit 3 (End of Study)
This visit will last approximately 2 hours at the Joslin Diabetes Center. The visit will include the following:
Review medical history, including any updates since the last visit. Physical examination, vital signs (blood pressure, heart rate, temperature, height and weight) and an otoscopic exam (a look inside the external ear).
Review of diaries the participant completed during the study. The participant will be asked to complete the same surveys as at Visit 1 and additional surveys about the experience with the device.
The participant will return study devices to the study team so the information can be downloaded for analysis.
The investigator will review the glucose monitoring information with the participant at the end of this visit, but will not be able to review data from the ear device.
706 studies on the registry are indexed under Hypoglycemia; 94 are open to participants now.
This study's planned enrollment of 5 is below the median of 86 across 131 observational studies indexed under Hypoglycemia.
Browse Hypoglycemia studies →Joslin Diabetes Center is the lead sponsor of 80 studies on the registry; 7 are open to participants now.
Counted across the registry records on this site, refreshed daily.
healthy individuals without hypoglycemia or upper gastrointestinal surgery
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
individuals with no history of hypoglycemia or upper gastrointestinal surgery
Device: in-ear device measuring blood flow
A small in-ear wearable device will be placed to monitor the blood flow to the head. The investigators will make sure it fits comfortably and show the participant how to use it properly. Dexcom G6 Pro: This continuous glucose monitor (CGM) will be placed under the skin of the abdomen to monitor sensor sugar levels. These sensors will be placed during visit one and will be worn together for 10 days. A followup visit (visit 2) will occur remotely at 4-6 days later. A final visit will occur after 10 days when the device will be removed.
Rate of study completion
Feasibility as determined by rate of study completion
Time frame: up to 10 days
Number of days with viable data (complete recordings)
Feasibility as determined by number of days with viable data (complete recordings)
Time frame: up to 10 days
Participant-reported outcome scores
Scores from a qualitative survey (Patient-Reported Outcomes for In-Ear Device, adapted from the COPROD questionnaire (COnfort des PROtections auDitives/COmfort of hearing PROtection Devices) of patient acceptance of in-ear wearable device at study completion.
Time frame: up to 10 days
Correlation between external cerebral blood flow (eCBF) (arbitrary units) and corresponding sensor glucose values (mg/dL)
Determine correlation between external cerebral blood flow (arbitrary units) and nearest sensor glucose levels (mg/dL), summed over the length of wear for each participant
Time frame: up to 10 days
Correlation between rate of change in eCBF (arbitrary units) and rate of change in sensor glucose (mg/dL)
Determine correlation between rate of change from baseline in eCBF and rate of change in sensor glucose values, summed over the length of wear for each participant
Time frame: up to 10 days
Success of data transfer from ear device to study database
Success of blood flow data transfer (yes/no) from ear device to study database for each participant
Time frame: up to 10 days
Percentage of time with successful blood flow (arbitrary units) data collection
The percentage of time with successful data collection, normalized to total wear time (hours)
Time frame: up to 10 days
Change in eCBF over 3 hours after meal initiation
Change in eCBF over 3 hours after meal initiation, as compared with mean eCBF over 1 hour prior to meal ingestion
Time frame: up to 10 days
Change in eCBF during physical activity, measured by integrated eCBF changes from onset of activity to completion of activity.
Change in eCBF from baseline during physical activity, measured by integrated eCBF changes from onset of activity to completion of activity
Time frame: up to 10 days
Correlation of hypoglycemia symptom score, measured by the Edinburgh Hypoglycemia Scale (EHHS) at study entry, with the frequency of low sensor glucose readings (% of time with sensor glucose < 70 mg/dL)
The total Edinburgh Hypoglycemia Score (obtained via survey at study entry) will be correlated with the % of time with sensor glucose readings below 70 mg/dL) for each participant
Time frame: up to 10 days
Correlation of dysautonomia symptom score, measured by the COMPASS survey at study entry, with the frequency of low sensor glucose readings (% of time with sensor glucose <70 mg/dL)
The COMPASS score will be correlated with the % of time with sensor glucose readings below 70 mg/dL for each participant.
Time frame: up to 10 days
Correlation of hypoglycemia symptom score, measured by the Edinburgh Hypoglycemia Score at study entry, with the coefficient of variation in eCBF (SD/mean) over the duration of the study
The EHSS score will be correlated with the coefficient of variation in eCBF over the duration of the study
Time frame: up to 10 days
Correlation of dysautonomia symptom score, measured by the COMPASS survey at study entry, with the coefficient of variation in eCBF (SD/mean) over the duration of the study
The COMPASS score will be correlated with the coefficient of variation in eCBF over the duration of the study.
Time frame: up to 10 days
Number of participants with treatment-related adverse events as assessed by CTCAE v4.0
Adverse events will be recorded and graded for severity and relatedness by study staff during course of study
Time frame: through study completion, up to 10 days
Plan to share: No — Individual participant data will not be shared for this pilot study.
Started Jul 2025 (actual). Primary completion is estimated for Sep 2026, 13 months after the start.
Of 52 non-industry observational studies under Hypoglycemia, half reached primary completion within 22 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 52. This study's planned 13 months is below that.
Counting every sponsor, half of 53 studies reached it within 22 months; a quarter within 12 and three quarters within 52.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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