External Carotid Blood Flow in Individuals With Post-Bariatric Hypoglycemia

NCT07082478 | Recruiting

• 1 other identifier: STUDY00000303
• Study Type: observational
• Target: 5
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Hypoglycemia; Cerebral Blood Flow

Keywords

hypoglycemia; postprandial hypoglycemia; bariatric surgery; autonomic dysfunction; cerebral blood flow

Outcome Measures

Primary Outcomes (5)

• Rate of study completion

  Feasibility as determined by rate of study completion

  up to 10 days

• Number of days with viable data (complete recordings)

  Feasibility as determined by number of days with viable data (complete recordings)

  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.

  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

  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

  up to 10 days

Secondary Outcomes (8)

• Success of data transfer from ear device to study database

  up to 10 days

• Percentage of time with successful blood flow (arbitrary units) data collection

  up to 10 days

• Change in eCBF over 3 hours after meal initiation

  up to 10 days

• Change in eCBF during physical activity, measured by integrated eCBF changes from onset of activity to completion of activity.

  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)

  up to 10 days

Other Outcomes (1)

• Number of participants with treatment-related adverse events as assessed by CTCAE v4.0

  through study completion, up to 10 days

Study Arms (1)

healthy individuals

individuals with no history of hypoglycemia or upper gastrointestinal surgery

Device: in-ear device measuring blood flow

Interventions

in-ear device measuring blood flow DEVICE

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.

healthy individuals

Eligibility Criteria

• Age: 18 Years - 70 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

healthy individuals without hypoglycemia or upper gastrointestinal surgery

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• Joslin Diabetes Center: lead

Study Sites (1)

Joslin Diabetes Center

Boston, Massachusetts, 02215, United States

RECRUITING

Related Publications (9)

• Gold AE, MacLeod KM, Frier BM. Frequency of severe hypoglycemia in patients with type I diabetes with impaired awareness of hypoglycemia. Diabetes Care. 1994 Jul;17(7):697-703. doi: 10.2337/diacare.17.7.697.

  PMID: 7924780 BACKGROUND

• Kaufmann H, Malamut R, Norcliffe-Kaufmann L, Rosa K, Freeman R. The Orthostatic Hypotension Questionnaire (OHQ): validation of a novel symptom assessment scale. Clin Auton Res. 2012 Apr;22(2):79-90. doi: 10.1007/s10286-011-0146-2. Epub 2011 Nov 2.

  PMID: 22045363 BACKGROUND

• Sletten DM, Suarez GA, Low PA, Mandrekar J, Singer W. COMPASS 31: a refined and abbreviated Composite Autonomic Symptom Score. Mayo Clin Proc. 2012 Dec;87(12):1196-201. doi: 10.1016/j.mayocp.2012.10.013.

  PMID: 23218087 BACKGROUND

• Laurenius A, Olbers T, Naslund I, Karlsson J. Dumping syndrome following gastric bypass: validation of the dumping symptom rating scale. Obes Surg. 2013 Jun;23(6):740-55. doi: 10.1007/s11695-012-0856-0.

  PMID: 23315151 BACKGROUND

• Deary IJ, Hepburn DA, MacLeod KM, Frier BM. Partitioning the symptoms of hypoglycaemia using multi-sample confirmatory factor analysis. Diabetologia. 1993 Aug;36(8):771-7. doi: 10.1007/BF00401150.

  PMID: 8405746 BACKGROUND

• Addison P, Carsky K, Patti ME, Roslin M. Hypoglycemia and Dysautonomia After Bariatric Surgery: a Systematic Review and Perspective. Obes Surg. 2022 May;32(5):1681-1688. doi: 10.1007/s11695-022-05960-x. Epub 2022 Feb 8.

  PMID: 35133603 BACKGROUND

• Zhang JB, Tamboli RA, Albaugh VL, Williams DB, Kilkelly DM, Grijalva CG, Shibao CA. The incidence of orthostatic intolerance after bariatric surgery. Obes Sci Pract. 2019 Dec 6;6(1):76-83. doi: 10.1002/osp4.383. eCollection 2020 Feb.

  PMID: 32128245 BACKGROUND

• Tripathi H, Gonuguntla A, Lee D, Fudim M, Brinker J, Tandri H. Monitoring Carotid Blood Flow Using In-Ear Wearable Device During Tilt-Table Testing. JACC Clin Electrophysiol. 2023 May;9(5):710-712. doi: 10.1016/j.jacep.2023.02.002. Epub 2023 Mar 22. No abstract available.

  PMID: 36951817 BACKGROUND

• An Z, Wang H, Mokadem M. Role of the Autonomic Nervous System in Mechanism of Energy and Glucose Regulation Post Bariatric Surgery. Front Neurosci. 2021 Nov 23;15:770690. doi: 10.3389/fnins.2021.770690. eCollection 2021.

  PMID: 34887725 BACKGROUND

MeSH Terms

Conditions

Hypoglycemia; Primary Dysautonomias

Condition Hierarchy (Ancestors)

Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases; Autonomic Nervous System Diseases; Nervous System Diseases

Study Officials

• Mary E Patti, M.D.

  Joslin Diabetes Center

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Gabriela Londono, B.S.

CONTACT

6173091940; glondono@joslin.harvard.edu

Lily Swaine-Moore, B.S.

CONTACT

6173094468; lswainem@joslin.harvard.edu

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Senior Investigator

Study Record Dates

• First Submitted: June 10, 2025
• First Posted: July 24, 2025
• Study Start: July 28, 2025
• Primary Completion (Estimated): September 15, 2026
• Study Completion (Estimated): September 15, 2026
• Last Updated: November 28, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)