NCT07082478 · Joslin Diabetes Center
External Carotid Blood Flow in Individuals With Post-Bariatric Hypoglycemia
What this study is about
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.
View original scientific description
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.
Interventions
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.
Primary outcome measures
Rate of study completion
Time frame: up to 10 days
Feasibility as determined by rate of study completion
Number of days with viable data (complete recordings)
Time frame: up to 10 days
Feasibility as determined by number of days with viable data (complete recordings)
Participant-reported outcome scores
Time frame: up to 10 days
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.
Correlation between external cerebral blood flow (eCBF) (arbitrary units) and corresponding sensor glucose values (mg/dL)
Time frame: up to 10 days
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
Correlation between rate of change in eCBF (arbitrary units) and rate of change in sensor glucose (mg/dL)
Time frame: up to 10 days
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
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Age 18-70 years of age, inclusive at screening.
- Individuals able to provide informed consent and follow all study procedures, including complete daily food, activity, and symptom diaries, and willingness to provide access to medical record review.
- For healthy control group: individuals without a history of upper gastrointestinal surgery and without reported symptoms of hypoglycemia.
- Individuals with access to personal iPhone running operating system 16 (iOS) or later versions (not feasible for Android platform users) and a password-protected home Wi-Fi network.
Exclusion criteria
- History of coronary artery disease or presence of 2 or more risk factors including diabetes, uncontrolled hypertension, uncontrolled hyperlipidemia, and active tobacco use.
- History of myocardial infarction, unstable angina or revascularization within the past 6 months.
- History of syncope (unrelated to hypoglycemia) or diagnosed cardiac arrhythmia.
- Documented hypoglycemia occurring in the fasting state (\> 12 hours fast).
- Concurrent administration of β-blocker therapy.
- Vigorous physical activity within 24 hours prior to assessment.
- Seizure disorder (other than with suspect or documented hypoglycemia).
- Hematocrit \< 33% (women) or \<36% (men) within the past 6 months.
- History of insulinoma.
- Use of central nervous system-active medications, including: antidepressants, anxiolytics, antipsychotics, stimulants, antiepileptics, sedatives and opioids.
- History of severe neurologic vascular disease (e.g. cerebrovascular disease/stroke).
- History of previous diseases associated with dysautonomia (e.g. multiple system atrophy, multiple sclerosis, Parkinson's disease).
- Impaired hepatic function (aspartate amino transaminase and/or alanine amino transaminase \>2x upper limit of normal range), as determined within the past 6 months.
- Impaired renal function (serum creatinine \>1.5 mg/dL), as determined within the past 6 months.
- Serious psychiatric or substance abuse disorders (e.g. alcohol, opioid, cocaine use disorder), as judged by the study investigator.
- Non-consent or inability to comply with study procedures.
- Current pregnancy and/ or lactation.
- Vulnerable individuals (e.g., fetuses, children, prisoners) and those judged by the investigator to be unsuitable for the study.
- Individuals wearing earrings or other jewelry in the left ear who are unable or unwilling to remove them for the duration of the study.
- Unwillingness to wear study masked CGM for duration of study
Where
- Boston, Massachusetts
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Nov 28, 2025 · Source of record for eligibility and locations