Diet Treatment Glucose Transporter Type 1 Deficiency (G1D)

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: Completed
• Conditions: Glucose Metabolism Disorders; Epilepsy; Glucose Transporter Type 1 Deficiency Syndrome; Glut1 Deficiency Syndrome 1, Autosomal Recessive; Glucose Transporter Protein Type 1 Deficiency Syndrome; Glucose Transport Defect; GLUT1DS1
• Intervention / Treatment: Drug: Triheptanoin

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: Interventional
• Enrollment (Actual): 45
• Phase: Phase 2

Contacts and Locations

Study Locations

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

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Neuropsychological Score of Sustained Attention	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	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)	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)	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)	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)	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

Outcome Measure	Measure Description	Time Frame
EEG Changes: Generalized Spike Wave Activity and Burst	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	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	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	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	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	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

• Sponsor: University of Texas Southwestern Medical Center
• Collaborators: National Institute of Neurological Disorders and Stroke (NINDS)
• Investigators: Principal Investigator: Juan Pascual, MD, Study Principal Investigator

Publications and helpful links

General Publications

• Pascual JM, Liu P, Mao D, Kelly DI, Hernandez A, Sheng M, Good LB, Ma Q, Marin-Valencia I, Zhang X, Park JY, Hynan LS, Stavinoha P, Roe CR, Lu H. Triheptanoin for glucose transporter type I deficiency (G1D): modulation of human ictogenesis, cerebral metabolic rate, and cognitive indices by a food supplement. JAMA Neurol. 2014 Oct;71(10):1255-65. doi: 10.1001/jamaneurol.2014.1584.
• Pascual JM, Ronen GM. Glucose Transporter Type I Deficiency (G1D) at 25 (1990-2015): Presumptions, Facts, and the Lives of Persons With This Rare Disease. Pediatr Neurol. 2015 Nov;53(5):379-93. doi: 10.1016/j.pediatrneurol.2015.08.001. Epub 2015 Aug 10.
• Hao J, Kelly DI, Su J, Pascual JM. Clinical Aspects of Glucose Transporter Type 1 Deficiency: Information From a Global Registry. JAMA Neurol. 2017 Jun 1;74(6):727-732. doi: 10.1001/jamaneurol.2017.0298.

Study record dates

Study Major Dates

• Study Start (Actual): April 18, 2018
• Primary Completion (Actual): September 10, 2023
• Study Completion (Actual): September 10, 2023

Study Registration Dates

• First Submitted: April 25, 2017
• First Submitted That Met QC Criteria: June 6, 2017
• First Posted (Actual): June 8, 2017

Study Record Updates

• Last Update Posted (Actual): August 7, 2025
• Last Update Submitted That Met QC Criteria: July 28, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pathologic Processes; Disease; Syndrome; Metabolic Diseases; Glucose Metabolism Disorders
• Other Study ID 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