Diet Treatment Glucose Transporter Type 1 Deficiency (G1D)

July 28, 2025 updated by: Juan Pascual, University of Texas Southwestern Medical Center

Dietary Treatment of Glucose Transporter Type 1 Deficiency (G1D)

Forty-five subjects receiving no dietary therapy with a proven G1D diagnosis will be enrolled. To evaluate the effect of C7 supplementation of a regular diet on a EEG activity in addition to IQ, language, working memory, processing speed, emotional and behavioral functioning, ataxia, and other neuropsychological and neurological performance indices in children and adults genetically diagnosed with G1D receiving a regular diet at enrollment.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This is an open-label, single arm trial of orally-administered C7 in G1D. Subjects will replace a fixed percentage of their daily caloric intake (based on the results of Protocol 1) with C7 for 6 months, undergo full evaluation and discontinuation of treatment at a 6 month visit, and return for an off-treatment follow up visit 3 months after C7 oil discontinuation, for total duration of participation of 9 months. Subjects will undergo treatment initiation on a 24-hour inpatient basis. During that 24-hr inpatient treatment initiation, subjects will have continuous EEG both to monitor for real-time seizure activity (for safety) and to determine EEG changes (secondary outcome) before, during, and after treatment initiation. Subjects will undergo clinical evaluation, comprehensive blood work, ataxia scale rating, EEG, and neuropsychological testing at baseline, 6 months, and 9 months.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
45

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Texas
      • Dallas, Texas, United States, 75390
        • University of Texas Southwestern Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

2 years to 35 years (Child, Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Diagnosis of glucose transporter type I deficiency (G1D), confirmed by clinical genotyping at a CLIA-certified laboratory or by PET scan.
  • Stable diet on either a modified atkins diet or on no dietary therapy (i.e., no dietary therapy for 1 month).
  • Males and females 24 months to 35 years old, inclusive.

Exclusion Criteria:

  • Subjects with evidence of independent, unrelated metabolic and/or genetic disease.
  • Subjects with a chronic gastrointestinal disorder, such as irritable bowel syndrome, Crohn's disease, or colitis that could increase the subject's risk of developing diarrhea or stomach pain.
  • Subjects with a BMI (body mass index) greater than or equal to 30.
  • Subjects currently on dietary therapy (i.e., ketogenic diet, medium chain triglyceride supplemented diets, Atkins diet, low glycemic index diet).
  • Subjects with no evidence of abnormal EEG (spike wave discharges) in the last 12 months.
  • Women who are pregnant or breast-feeding may not participate. Women who plan to become pregnant during the course of the study, or who are unwilling to use birth control to prevent pregnancy (including abstinence) may not participate. Females age 10 and over will be asked to provide a urine sample for a pregnancy test via dipstick. Subjects will be asked to agree to abstinence or another form of birth control for the duration of the study.
  • Allergy/sensitivity to C7.
  • Previous use of triheptanoin in the past 1 month. Subjects who participate in Protocol 1 of this study are thus eligible.
  • Subjects exhibiting signs of dementia, or diagnosed with any degenerative brain disorder (such as Alzheimer's disease) that would confound assessment of cognitive changes, in the opinion of the investigator.
  • Active drug or alcohol use or dependence that, in the opinion of the investigator, would interfere with adherence to study requirements.
  • Inability or unwillingness of subject or legal guardian/representative to give written informed consent, or assent for children age 10-17.
  • Addition of a new antiseizure drug in the previous 3 months.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Triheptanoin
This is a single arm study.
Drug: Triheptanoin
. Triheptanoin will be taken 4 times per day (approximately every 6 hours: prior to breakfast, lunch and dinner and a mid-afternoon snack) by mouth. It is dosed 4 times per day, divided evenly.
Other Names:
  • C7

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Neuropsychological Score of Sustained Attention
Time Frame: Change post 6 months of treatment
Sustained attention was evaluated using a subtest of Conners' Kiddie Continuous Performance Test Second Edition (K-CPT 2): CPT-Hit Reaction Time Block Change. CPT HRT BC indicates the change in mean response speed as the administration of the test progresses in blocks. A decrease in CPT HRT BC indicates a decrease in reaction time, which means the participant's information processing efficiency increases, and an improvement in sustained attention is noted. The number of participants that showed a decrease in the CPT HRT BC score after 6 months of treatment as compared to baseline is noted here.
Change post 6 months of treatment
Neuropsychological Score of Sustained Attention
Time Frame: Change after 3 months off treatment
Sustained attention was evaluated using a subtest of Conners' Kiddie Continuous Performance Test Second Edition (K-CPT 2): CPT-Hit Reaction Time Block Change. CPT HRT BC indicates the change in mean response speed as the administration of the test progresses in blocks. A decrease in CPT HRT BC indicates a decrease in reaction time, which means the participant's information processing efficiency increases, and an improvement in sustained attention is noted. The off-treatment period of 3 months was implemented to study whether the impact of treatment persists or goes back to baseline. The number of patients that displayed an increase in CPT HRT BC score (towards baseline) after 3 months off treatment as compared to 6 months on treatment is noted here.
Change after 3 months off treatment
Neuropsychological Score of Working Memory Index Scale (WMI)
Time Frame: Change post 6 months of treatment
Subjects were administered the Working Memory Index Scale (WMI) from either the Wechsler Primary and Preschool Scale of Intelligence, 4th Edition (WPPSI-IV), Wechsler Intelligence Scale for Children, 5th Edition (WISC-V), or the Wechsler Adult Intelligence Scale, 4th Edition (WAIS-IV) according to the age of subject. An increase WMI score would indicate an improvement in the cognitive ability of identifying, reorganizing and retaining information for a brief period of time. The number of participants that showed an increase in the WMI score after 6 months of treatment is noted here.
Change post 6 months of treatment
Neuropsychological Score of Working Memory Index Scale (WMI)
Time Frame: Change after 3 months off-treatment
Subjects were administered the Working Memory Index Scale (WMI) from either the Wechsler Primary and Preschool Scale of Intelligence, 4th Edition (WPPSI-IV), Wechsler Intelligence Scale for Children, 5th Edition (WISC-V), or the Wechsler Adult Intelligence Scale, 4th Edition (WAIS-IV) according to the age of subject. An increase WMI score would indicate an improvement in the cognitive ability of identifying, reorganizing and retaining information for a brief period of time. The 3 months off-treatment period was designed to study whether the impact of treatment persists or goes back to baseline. The number of participants that showed a decrease in the WMI score after 3 months off treatment as compared to 6 months on treatment was calculated.
Change after 3 months off-treatment
Neuropsychological Score of Processing Speed Index (PSI)
Time Frame: Change post 6 months of treatment
Subjects were administered the Processing Speed Index Scale (PSI) from either the Wechsler Primary and Preschool Scale of Intelligence, 4th Edition (WPPSI-IV), Wechsler Intelligence Scale for Children, 5th Edition (WISC-V) or the Wechsler Adult Intelligence Scale, 4th Edition (WAIS-IV) according to the age of subject. An increase PSI score would indicate an improvement in the motor-based estimate of the subject's cognitive processing speed. The number of participants that showed an increase in the PSI score after 6 months of treatment as compared to baseline is noted here.
Change post 6 months of treatment
Neuropsychological Score of Processing Speed Index (PSI)
Time Frame: Change after 3 months off-treatment
Subjects were administered the Processing Speed Index Scale (PSI) from either the Wechsler Primary and Preschool Scale of Intelligence, 4th Edition (WPPSI-IV), Wechsler Intelligence Scale for Children, 5th Edition (WISC-V) or the Wechsler Adult Intelligence Scale, 4th Edition (WAIS-IV) according to the age of subject. An increase PSI score would indicate an improvement in the motor-based estimate of the subject's cognitive processing speed. The 3 months off-treatment period was designed to study whether the impact of treatment persists or goes back to baseline. The number of participants that showed a decrease in the WMI score after 3 months off treatment as compared to 6 months on treatment was calculated.
Change after 3 months off-treatment

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
EEG Changes: Generalized Spike Wave Activity and Burst
Time Frame: Change post 6 months of treatment
The number of generalized spike wave (GSW) activity and bursts were extracted from the patient EEGs. GSW and bursts per hour was calculated. A decrease in the spike wave and burst indicated an improvement. The number of patients that displayed a decrease in GSW and burst per hour after 6 months of treatment in noted here.
Change post 6 months of treatment
EEG Changes: Generalized Spike Wave Activity and Burst
Time Frame: Change after 3 months off-treatment
The number of generalized spike wave (GSW) activity and bursts were extracted from the patient EEGs. GSW and bursts per hour was calculated. A decrease in the spike wave and burst indicated an improvement. The off-treatment period of 3 months was implemented to study whether the impact of treatment persists or goes back to baseline. The number of patients that displayed an increase in GSW and burst per hour (towards baseline) after 3 months off treatment as compared to 6 months on treatment is noted here.
Change after 3 months off-treatment
Brief Ataxia Rating Scale
Time Frame: Change post 6 months of treatment
Ataxia is scored as per the Brief ataxia rating scale (BARS) - a modified form of the International Cooperative Ataxia Rating Scale (ICARS). The possible range for the scores is from 0 (normal, no ataxia) to 30 (severe ataxia). A decrease in the BARS score indicates an improvement in the ataxia symptoms. The number of participants that showed a decrease in BARS score after 6 months of intervention is reported here.
Change post 6 months of treatment
Brief Ataxia Rating Scale
Time Frame: Change after 3 months off treatment
Ataxia is scored as per the Brief ataxia rating scale (BARS) - a modified form of the International Cooperative Ataxia Rating Scale (ICARS). The possible range for the scores is from 0 (normal, no ataxia) to 30 (severe ataxia). A decrease in the BARS score indicates an improvement in the ataxia symptoms. The off-treatment period of 3 months was implemented to study whether the impact of treatment persists or goes back to baseline. The number of participants that showed a subsequent increase in BARS score (towards baseline) after the of 3 months of no treatment as compared to 6 months on treatment are recorded here.
Change after 3 months off treatment
Clinical Global Impression Severity Scale
Time Frame: Change post 6 months of treatment
The Clinical global impression - Severity (CGI-S) scale is used to evaluate the illness severity where the scores range from 1 (very much improved) through to 7 (very much worse). A decrease in the CGI-S score indicates a decrease in illness severity. The number of participants that showed a decrease in CGI-S score after 6 months of intervention as compared to baseline is reported here.
Change post 6 months of treatment
Clinical Global Impression Severity Scale
Time Frame: Change after 3 months off-treatment
The Clinical global impression - Severity (CGI-S) scale is used to evaluate the illness severity where the scores range from 1 (very much improved) through to 7 (very much worse). A decrease in the CGI-S score indicates a decrease in illness severity. The off-treatment period of 3 months was designed to study whether the impact of treatment persists or goes back to baseline. The number of participants that showed an increase in CGI-S score (towards baseline) after 3 months off treatment as compared to 6 months on treatment is reported
Change after 3 months off-treatment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Texas Southwestern Medical Center

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute of Neurological Disorders and Stroke (NINDS)

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Juan Pascual, MD, Study Principal Investigator

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 18, 2018

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 10, 2023

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 10, 2023

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 25, 2017

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 6, 2017

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
June 8, 2017

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 7, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 28, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 122016-013
  • 1R01NS094257-01A1 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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