Glucose Metabolism Disorders
Conditions
Brief summary
Purpose: In this study, the investigators will delineate how brain network dynamics are modulated by experimentally induced elevated blood glucose levels and examine how glucose levels gate neuronal excitability measured by the response to TMS. Participants: Participants must be between the ages of 18 and 65 with no known diabetes, no known adverse reaction to finger prick blood draw, and no known neurological or psychiatric illness. Participants must have a body-mass index less than 30. Procedures: Participants will consume either a drink that contains 75 g of glucose or a placebo, and their response to TMS will be measured to examine the effect of glucose on motor cortex excitability.
Detailed description
This study will be a placebo-controlled study that investigates brain function with both electroencephalography (EEG) and TMS. On each study visit, a drink (either glucose drink or water) is administered after baseline assessment of fasting glucose. Changes in brain activity and excitability will be measured with resting-state EEG. Periodic high-density EEG of resting-state brain activity and activity during a working memory task will be performed before the administration of the drink, immediately after the administration of the drink, as well as 30 minutes, 60 minutes, 120 minutes, 150 minutes, and 180 minutes after the administration of the drink. The spectral content of the EEG signal will be investigated to identify the relative presence of cortical oscillations. Primarily, there will be a focus on theta (4-8 Hz) and alpha (8-12 Hz) oscillations. Previous literature indicates that theta and alpha oscillations represent an engaged and disengaged cortical state, respectively \[1\]. Alpha and theta oscillations are implicated in cognitive function and are altered in depression. Therefore, this study aims to identify a decrease in frontal theta oscillations and an increase in left frontal alpha oscillations, two defining features of impaired top-down control and mood regulation, in response to the glucose drink contrasted with the response to the placebo. The study will also examine how glucose levels gate neuronal excitability measured by the response to TMS. Cortical excitability will be measured by applying TMS pulses to the motor cortex and measuring the response in the form of a motor evoked potential by electromyography (EMG). TMS will be applied before the administration of the drink, immediately after the administration of the drink, as well as 30 minutes, 60 minutes, 120 minutes, 150 minutes, and 180 minutes after the administration of the drink. Changes in blood glucose will be monitored over this time interval as well.
Interventions
DEVICESingle-pulse TMS
Single-pulse transcranial magnetic stimulation (TMS) on the motor cortex will lead to a twitch in the target muscle and evoke a motor-evoked potential (MEP) measured by electromyography (EMG).
Sponsors
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
University of North Carolina, Chapel Hill
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Investigator)
Masking description
The researcher that interacts with the subject will not know whether the subject consumed the glucose drink or the placebo.
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
* Right-handed * BMI \<30 * Free of major neurological conditions and diabetes
Exclusion criteria
* Diabetes * Adverse reaction to finger prick blood draw * Known neurological or psychiatric illness * Prior brain surgery * Any brain devices/implants, including cochlear implants and aneurysm clips * Cardiac pacemaker * Any other implanted electronic device * History of current traumatic brain injury * Anything that, in the opinion of the investigator, would place the participant at increased risk or preclude the participant's full compliance with or completion of the study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Motor Evoked Potential (MEP) | Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink. | Change in MEP over time to indicate changes in motor cortex excitability |
| TMS Evoked Potential (TEP) | Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink. | The TMS Evoked Potential (TEP) is the difference in microvolts from 25 milliseconds after a TMS pulse versus pre-TMS such that greater values indicate greater motor cortex excitability. The measure of the change in TEP over time since either glucose or water was consumed approximates a z-distribution with a range of -20 to 20 with central distribution measures of zero. TEPs were source localized and reported using a pseudo-neural activity index (PNAI) expressing source activation in relation to pre-TMS pulse trial baseline. The difference in the source peaks corresponding to the early P25 component have been reported as differences from baseline. Higher values indicate greater cortical excitation, consistent with the study hypothesis. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| EEG Measure of Alpha Asymmetry Oscillations | Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink. | Electroencephalography will be used to measure the change in lateralized alpha asymmetry (10-12 Hz electrical activity) over time |
| EEG Measure of Frontal Midline Theta Oscillations | Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink. | Electroencephalography will be used to measure the change in frontal midline theta power (5-8 Hz electrical activity) over time |
| Working Memory Task Accuracy | Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink. | This outcome will analyze the change in accuracy in a computerized working memory task over time. During the task, subjects will be presented with an array of colored squares. Then, they will need to hold this array in mind during a delay period. Finally, participants will be tested on their memory of the array by responding whether a presented color is the same or different as the corresponding square in the first array. Participants' accuracy will be expressed as the percentage of correct responses (from 0% correct responses to 100% correct responses). An accuracy rate of 50% indicates that the participant is performing at the same accuracy level as random chance. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| All Participants Participants will consume the glucose drink at session 1, then they will consume the placebo (water) at session 2, or vice versa.
Single-pulse TMS: Single-pulse transcranial magnetic stimulation (TMS) on the motor cortex will lead to a twitch in the target muscle and evoke a motor-evoked potential (MEP) measured by electromyography (EMG). | 23 |
| Total | 23 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Baseline | Did not meet full inclusion/exclusion. | 2 | 4 |
| Baseline | Lost to Follow-up | 0 | 1 |
| Pre-randomization | Disqualified by TMS safety screening | 1 | 0 |
| Pre-randomization | Withdrawn for COVID19 precautions | 1 | 3 |
| Washout (5 Day Min) | Lost to Follow-up | 1 | 0 |
Baseline characteristics
| Characteristic | All Participants |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 23 Participants |
| Age, Continuous | 24.64 years STANDARD_DEVIATION 10.49 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 1 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 21 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 1 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 5 Participants |
| Race (NIH/OMB) Black or African American | 4 Participants |
| Race (NIH/OMB) More than one race | 1 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 13 Participants |
| Region of Enrollment United States | 23 Participants |
| Sex: Female, Male Female | 15 Participants |
| Sex: Female, Male Male | 8 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 11 | 0 / 10 |
| other Total, other adverse events | 10 / 11 | 8 / 10 |
| serious Total, serious adverse events | 0 / 11 | 0 / 10 |
Outcome results
Primary
Motor Evoked Potential (MEP)
Change in MEP over time to indicate changes in motor cortex excitability
Time frame: Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink.
Population: From the 10 participants who completed, 3 were excluded from the analysis due to technical reasons. Two participants had to end their glucose visits early due to scheduling conflicts. The reported N below is adjusted where appropriate.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| MEP After Glucose Drink | Motor Evoked Potential (MEP) | MEP change (30 min vs pre-drink) | -0.02 log10(Post uV/Baseline uV) | Standard Error 0.19 |
| MEP After Glucose Drink | Motor Evoked Potential (MEP) | MEP change (120 min vs pre-drink) | -0.05 log10(Post uV/Baseline uV) | Standard Error 0.16 |
| MEP After Glucose Drink | Motor Evoked Potential (MEP) | MEP change (60 min vs pre-drink) | -0.08 log10(Post uV/Baseline uV) | Standard Error 0.14 |
| MEP After Glucose Drink | Motor Evoked Potential (MEP) | MEP change (180 min vs pre-drink) | -0.21 log10(Post uV/Baseline uV) | Standard Error 0.18 |
| MEP After Glucose Drink | Motor Evoked Potential (MEP) | MEP change (0 min vs pre-drink) | 0.14 log10(Post uV/Baseline uV) | Standard Error 0.15 |
| MEP After Placebo Drink | Motor Evoked Potential (MEP) | MEP change (180 min vs pre-drink) | -0.18 log10(Post uV/Baseline uV) | Standard Error 0.1 |
| MEP After Placebo Drink | Motor Evoked Potential (MEP) | MEP change (0 min vs pre-drink) | -0.25 log10(Post uV/Baseline uV) | Standard Error 0.07 |
| MEP After Placebo Drink | Motor Evoked Potential (MEP) | MEP change (30 min vs pre-drink) | -0.12 log10(Post uV/Baseline uV) | Standard Error 0.11 |
| MEP After Placebo Drink | Motor Evoked Potential (MEP) | MEP change (60 min vs pre-drink) | -0.33 log10(Post uV/Baseline uV) | Standard Error 0.1 |
| MEP After Placebo Drink | Motor Evoked Potential (MEP) | MEP change (120 min vs pre-drink) | -0.25 log10(Post uV/Baseline uV) | Standard Error 0.09 |
Primary
TMS Evoked Potential (TEP)
The TMS Evoked Potential (TEP) is the difference in microvolts from 25 milliseconds after a TMS pulse versus pre-TMS such that greater values indicate greater motor cortex excitability. The measure of the change in TEP over time since either glucose or water was consumed approximates a z-distribution with a range of -20 to 20 with central distribution measures of zero. TEPs were source localized and reported using a pseudo-neural activity index (PNAI) expressing source activation in relation to pre-TMS pulse trial baseline. The difference in the source peaks corresponding to the early P25 component have been reported as differences from baseline. Higher values indicate greater cortical excitation, consistent with the study hypothesis.
Time frame: Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink.
Population: From the 10 participants who completed, 3 were excluded from the analysis due to technical reasons. Two participants had to end their glucose visits early due to scheduling conflicts. The reported N below is adjusted where appropriate.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| MEP After Glucose Drink | TMS Evoked Potential (TEP) | TEP change (P25: 30 min vs pre-drink) | -0.11 z-score | Standard Error 0.11 |
| MEP After Glucose Drink | TMS Evoked Potential (TEP) | TEP change (P25: 120 min vs pre-drink) | -0.16 z-score | Standard Error 0.12 |
| MEP After Glucose Drink | TMS Evoked Potential (TEP) | TEP change (P25: 60 min vs pre-drink) | -0.16 z-score | Standard Error 0.11 |
| MEP After Glucose Drink | TMS Evoked Potential (TEP) | TEP change (P25: 180 min vs pre-drink) | 0.08 z-score | Standard Error 0.08 |
| MEP After Glucose Drink | TMS Evoked Potential (TEP) | TEP change (P25: 0 min vs pre-drink) | -0.04 z-score | Standard Error 0.08 |
| MEP After Placebo Drink | TMS Evoked Potential (TEP) | TEP change (P25: 180 min vs pre-drink) | 0.02 z-score | Standard Error 0.15 |
| MEP After Placebo Drink | TMS Evoked Potential (TEP) | TEP change (P25: 0 min vs pre-drink) | 0.28 z-score | Standard Error 0.16 |
| MEP After Placebo Drink | TMS Evoked Potential (TEP) | TEP change (P25: 30 min vs pre-drink) | 0.024 z-score | Standard Error 0.05 |
| MEP After Placebo Drink | TMS Evoked Potential (TEP) | TEP change (P25: 60 min vs pre-drink) | 0.30 z-score | Standard Error 0.06 |
| MEP After Placebo Drink | TMS Evoked Potential (TEP) | TEP change (P25: 120 min vs pre-drink) | 0.24 z-score | Standard Error 0.07 |
Secondary
EEG Measure of Alpha Asymmetry Oscillations
Electroencephalography will be used to measure the change in lateralized alpha asymmetry (10-12 Hz electrical activity) over time
Time frame: Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink.
Population: From the 10 participants who completed, one was excluded from the analysis due to technical reasons. Two participants had to end their glucose visits early due to scheduling conflicts. The reported N below is adjusted where appropriate.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| MEP After Glucose Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (30 min vs Baseline) | -0.01 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.2 |
| MEP After Glucose Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (120 min vs Baseline) | 0.18 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.22 |
| MEP After Glucose Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (60 min vs Baseline) | 0.14 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.22 |
| MEP After Glucose Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (180 min vs Baseline) | 0.18 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.33 |
| MEP After Glucose Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (0 min vs Baseline) | 0.15 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.15 |
| MEP After Placebo Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (180 min vs Baseline) | 0.28 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.33 |
| MEP After Placebo Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (0 min vs Baseline) | 0.59 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.45 |
| MEP After Placebo Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (30 min vs Baseline) | 0.42 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.42 |
| MEP After Placebo Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (60 min vs Baseline) | 0.19 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.25 |
| MEP After Placebo Drink | EEG Measure of Alpha Asymmetry Oscillations | Alpha Asymm. Change (120 min vs Baseline) | 0.33 10*log10(Right Alpha/Left Alpha) (uV) | Standard Error 0.22 |
Secondary
EEG Measure of Frontal Midline Theta Oscillations
Electroencephalography will be used to measure the change in frontal midline theta power (5-8 Hz electrical activity) over time
Time frame: Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink.
Population: From the 10 participants who completed, one was excluded from the analysis due to technical reasons. Two participants had to end their glucose visits early due to scheduling conflicts. The reported N below is adjusted where appropriate.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| MEP After Glucose Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (30 min vs Baseline) | 0.56 10*log10(Post uV/Baseline uV) | Standard Error 0.25 |
| MEP After Glucose Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (120 min vs Baseline) | 0.36 10*log10(Post uV/Baseline uV) | Standard Error 0.26 |
| MEP After Glucose Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (60 min vs Baseline) | 0.94 10*log10(Post uV/Baseline uV) | Standard Error 0.29 |
| MEP After Glucose Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (180 min vs Baseline) | 1.48 10*log10(Post uV/Baseline uV) | Standard Error 0.32 |
| MEP After Glucose Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (0 min vs Baseline) | 0.12 10*log10(Post uV/Baseline uV) | Standard Error 0.34 |
| MEP After Placebo Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (180 min vs Baseline) | 0.72 10*log10(Post uV/Baseline uV) | Standard Error 0.34 |
| MEP After Placebo Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (30 min vs Baseline) | 0.57 10*log10(Post uV/Baseline uV) | Standard Error 0.27 |
| MEP After Placebo Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (60 min vs Baseline) | 1.15 10*log10(Post uV/Baseline uV) | Standard Error 0.32 |
| MEP After Placebo Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (120 min vs Baseline) | 1.21 10*log10(Post uV/Baseline uV) | Standard Error 0.45 |
| MEP After Placebo Drink | EEG Measure of Frontal Midline Theta Oscillations | Theta Power Change (0 min vs Baseline) | 0.33 10*log10(Post uV/Baseline uV) | Standard Error 0.28 |
Secondary
Working Memory Task Accuracy
This outcome will analyze the change in accuracy in a computerized working memory task over time. During the task, subjects will be presented with an array of colored squares. Then, they will need to hold this array in mind during a delay period. Finally, participants will be tested on their memory of the array by responding whether a presented color is the same or different as the corresponding square in the first array. Participants' accuracy will be expressed as the percentage of correct responses (from 0% correct responses to 100% correct responses). An accuracy rate of 50% indicates that the participant is performing at the same accuracy level as random chance.
Time frame: Measurements will be taken before the administration of the drink, as well as 0, 30, 60, 120, and 180 minutes after the administration of the drink.
Population: From the 10 participants who completed, one was excluded from the analysis due to technical reasons. Two participants had to end their glucose visits early due to scheduling conflicts. The reported N below is adjusted where appropriate.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| MEP After Glucose Drink | Working Memory Task Accuracy | WM Accuracy (30 min vs Baseline) | 1.02 Ratio of correct responses | Standard Error 0.02 |
| MEP After Glucose Drink | Working Memory Task Accuracy | WM Accuracy (120 min vs Baseline) | 1.05 Ratio of correct responses | Standard Error 0.03 |
| MEP After Glucose Drink | Working Memory Task Accuracy | WM Accuracy (60 min vs Baseline) | 1.06 Ratio of correct responses | Standard Error 0.02 |
| MEP After Glucose Drink | Working Memory Task Accuracy | WM Accuracy (180 min vs Baseline) | 1.03 Ratio of correct responses | Standard Error 0.03 |
| MEP After Glucose Drink | Working Memory Task Accuracy | WM Accuracy (0 min vs Baseline) | 1.02 Ratio of correct responses | Standard Error 0.03 |
| MEP After Placebo Drink | Working Memory Task Accuracy | WM Accuracy (180 min vs Baseline) | 1.03 Ratio of correct responses | Standard Error 0.03 |
| MEP After Placebo Drink | Working Memory Task Accuracy | WM Accuracy (0 min vs Baseline) | 0.97 Ratio of correct responses | Standard Error 0.03 |
| MEP After Placebo Drink | Working Memory Task Accuracy | WM Accuracy (30 min vs Baseline) | 0.99 Ratio of correct responses | Standard Error 0.03 |
| MEP After Placebo Drink | Working Memory Task Accuracy | WM Accuracy (60 min vs Baseline) | 1.01 Ratio of correct responses | Standard Error 0.03 |
| MEP After Placebo Drink | Working Memory Task Accuracy | WM Accuracy (120 min vs Baseline) | 1.02 Ratio of correct responses | Standard Error 0.03 |