HIIT in Isolated IFG: A Proof-of-Concept Study

NCT ID: NCT06143345

Last Updated: 2026-01-09

Basic Information

• Recruitment Status: NOT_YET_RECRUITING
• Clinical Phase: NA
• Total Enrollment: 34 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2026-06-01
• Study Completion Date: 2026-12-30

Brief Summary

This pilot randomized controlled trial will involve 34 physically inactive adults aged 35-65 years with overweight or obesity and isolated impaired fasting glucose (i-IFG). The study aims to assess the feasibility of recruiting and retaining participants, implementing study procedures, and evaluating the acceptability of a high-intensity interval training (HIIT) intervention. Additionally, it will investigate the preliminary efficacy of HIIT in reducing fasting plasma glucose levels and addressing the pathophysiology of i-IFG.

Detailed Description

This 1:1 proof-of-concept randomized controlled trial (RCT) will involve 34 physically inactive adults aged 35-65 years who are overweight or obese and have isolated impaired fasting glycemia (i-IFG). Potentially eligible individuals identified through Emory's MyChart electronic health care records system will undergo initial screening via phone calls. Individuals meeting the eligibility criteria will be invited to the Georgia Clinical and Translational Science Alliance at Emory University Hospital in Atlanta for further assessment. During their visit, participants will complete questionnaires, undergo an oral glucose tolerance test, and provide blood samples for insulin. Individuals identified with i-IFG will be randomized into the intervention or control groups.

Individuals assigned to the intervention group will participate in supervised high-intensity interval training (HIIT) sessions using stationary Spin cycle ergometers, in groups of five or fewer. They will wear continuous glucose monitoring (CGM) devices for 10 days before the intervention, throughout the 8-week intervention period, and for 10 days post-intervention. The intervention will be conducted three times a week for eight weeks at the Aerobic Exercise Laboratory in the Rehabilitation Hospital at Emory University. Control participants will be instructed to refrain from engaging in intense physical activities during the study period and will also wear CGM devices for the same duration. All participants will receive instructions to maintain a eucaloric diet throughout the study.

At baseline and after eight weeks, all participants will undergo physical measurements (anthropometrics, blood pressure, and body composition) as well as biochemical measurements (glucose and insulin levels). Additionally, participants in the intervention group will be invited to participate in qualitative in-depth interviews both before and after the HIIT intervention and will complete an intervention acceptability questionnaire upon completion.

The primary outcomes include feasibility metrics, measures of intervention feasibility, acceptability, and appropriateness, and participants' experiences, perceptions, and satisfaction with the HIIT intervention, as well as facilitators and barriers to participation. Secondary outcomes include: 1) Between-group differences in changes from baseline to 8 weeks in mean fasting plasma glucose and insulin levels, indices of β-cell function and insulin resistance, and physical measurements; and 2) CGM metrics: a) Between-group differences in the proportion of time and mean time spent in nocturnal (00:00-06:00) [58] normoglycemia (60 to <100 mg/dl) during the 8-week intervention period and the 10 days following the intervention; b) Within-participant differences in the proportion of time and mean time spent in nocturnal (00:00-06:00) normoglycemia (60 to <100 mg/dl) between exercise and non-exercise days during the 8-week intervention period.

Conditions

Isolated Impaired Fasting Glucose

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: PREVENTION
• Blinding Strategy: SINGLE

Study Groups

Intervention Group

Intervention participants will complete 24 supervised high-intensity interval training (HIIT) sessions over 8 weeks, with 3 sessions per week on alternate days. Each HIIT session will consist of a 5-minute warm-up, followed by an interval-based workout phase that includes steady up-tempo cadences, sprints, and climbs, interspersed with recovery periods. The session will conclude with a 5-minute cooldown. The workout sessions will initially last 20 minutes and will progressively increase in time based on participants' tolerance and instructor recommendations. Intensity will start at 75% of the estimated maximal heart rate reserve and will increase by 5% weekly, as tolerated and/or deemed necessary by the instructor, over the 8-week intervention period. Participants will receive instructions to maintain a eucaloric diet throughout the study.

Group Type: EXPERIMENTAL

High-intensity interval training and eucaloric diet

Intervention Type: BEHAVIORAL

Intervention participants will complete 24 supervised high-intensity interval training (HIIT) sessions over 8 weeks, with 3 sessions per week on alternate days. Each HIIT session will consist of a 5-minute warm-up, followed by an interval-based workout phase that includes steady up-tempo cadences, sprints, and climbs, interspersed with recovery periods. The session will conclude with a 5-minute cooldown. The workout sessions will initially last 20 minutes and will progressively increase in time based on participants\&amp;#39; tolerance and instructor recommendations. Intensity will start at 75% of estimated maximal heart rate reserve and will increase by 5% weekly, as tolerated and/or deemed necessary by the instructor, over the 8-week intervention period. Participants will receive instructions to maintain a eucaloric diet throughout the study.

Continuous glucose monitoring (CGM) (Dexcom G6 Pro CGM sensor)

Intervention Type: DEVICE

The continuous glucose monitoring (CGM) system comprises a sensor, a transmitter, and a receiver. The sensor measures interstitial fluid glucose levels every 5 minutes, and the transmitter wirelessly sends this glucose data to the receiver. Both intervention and control participants will wear the CGM device in a blinded mode for 10 days before starting the intervention, throughout the 8-week intervention period, and for 10 days post-intervention.

Control Group

Control participants will be instructed to refrain from engaging in intense physical activities during the study period. They will also receive instructions to maintain a eucaloric diet throughout the study.

Group Type: ACTIVE_COMPARATOR

No intense physical activity and eucaloric diet

Intervention Type: BEHAVIORAL

Control participants will be instructed to refrain from engaging in intense physical activities during the study period. They will also receive instructions to maintain a eucaloric diet throughout the study.

Continuous glucose monitoring (CGM) (Dexcom G6 Pro CGM sensor)

Intervention Type: DEVICE

The continuous glucose monitoring (CGM) system comprises a sensor, a transmitter, and a receiver. The sensor measures interstitial fluid glucose levels every 5 minutes, and the transmitter wirelessly sends this glucose data to the receiver. Both intervention and control participants will wear the CGM device in a blinded mode for 10 days before starting the intervention, throughout the 8-week intervention period, and for 10 days post-intervention.

Interventions

High-intensity interval training and eucaloric diet

Intervention participants will complete 24 supervised high-intensity interval training (HIIT) sessions over 8 weeks, with 3 sessions per week on alternate days. Each HIIT session will consist of a 5-minute warm-up, followed by an interval-based workout phase that includes steady up-tempo cadences, sprints, and climbs, interspersed with recovery periods. The session will conclude with a 5-minute cooldown. The workout sessions will initially last 20 minutes and will progressively increase in time based on participants\&amp;#39; tolerance and instructor recommendations. Intensity will start at 75% of estimated maximal heart rate reserve and will increase by 5% weekly, as tolerated and/or deemed necessary by the instructor, over the 8-week intervention period. Participants will receive instructions to maintain a eucaloric diet throughout the study.

Intervention Type: BEHAVIORAL

No intense physical activity and eucaloric diet

Control participants will be instructed to refrain from engaging in intense physical activities during the study period. They will also receive instructions to maintain a eucaloric diet throughout the study.

Intervention Type: BEHAVIORAL

Continuous glucose monitoring (CGM) (Dexcom G6 Pro CGM sensor)

The continuous glucose monitoring (CGM) system comprises a sensor, a transmitter, and a receiver. The sensor measures interstitial fluid glucose levels every 5 minutes, and the transmitter wirelessly sends this glucose data to the receiver. Both intervention and control participants will wear the CGM device in a blinded mode for 10 days before starting the intervention, throughout the 8-week intervention period, and for 10 days post-intervention.

Intervention Type: DEVICE

Other Intervention Names

HIIT intervention; Dexcom G6 Pro CGM sensor

Eligibility Criteria

Inclusion Criteria

1. Males and females aged 35-65 years

2. Any race or ethnicity

3. BMI ≥25 kg/m2 (≥23 kg/m2 if Asian decent)

4. Physically inactive (<150 min of moderate-intensity or <75 min of vigorous-intensity aerobic physical activity/week)

5. Will be residing in the same location until completion of the study

6. Isolated impaired fasting glucose on the OGTT: FPG 100-125 mg/dl and 2-hr plasma glucose <140 mg/dl

Exclusion Criteria

1. History of diabetes

2. Regular exercise training in the past 6 months

3. Enrolled in weight loss programs in the past 6 months

4. Following a specific diet (e.g., ketogenic, Mediterranean)

5. Pregnant women

6. Breastfeeding

7. Smokers

8. Taking medications known to affect glucose tolerance (e.g., steroids)

9. Taking beta-blockers and calcium channel blockers

10. Taking weight loss medications

11. Underwent bariatric surgery

12. Anemia

13. History of chronic illnesses (e.g., stroke)

Individuals satisfying the eligibility criteria will undergo an OGTT (0, 30, 120 min), and those diagnosed with i-IFG (FPG 100 or 110-125 mg/dl and 2-hr PG <140 mg/dl) will be recruited to the study.

• Minimum Eligible Age: 35 Years
• Maximum Eligible Age: 65 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

National Center for Advancing Translational Sciences (NCATS)

NIH

Sponsor Role: collaborator

Emory University

OTHER

Sponsor Role: lead

Responsible Party

Sathish Thirunavukkarasu

Assistant Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Sathish Thirunavukkarasu, PhD

Role: PRINCIPAL_INVESTIGATOR

Emory University

Central Contacts

Sathish Thirunavukkarasu, PhD

Role: CONTACT

sathish.thirunavukkarasu@emory.edu

404-778-3771

References

Thirunavukkarasu S, Ziegler TR, Weber MB, Staimez L, Lobelo F, Millard-Stafford ML, Schmidt MD, Venkatachalam A, Bajpai R, El Fil F, Prokou M, Kumar S, Tapp RJ, Shaw JE, Pasquel FJ, Nocera JR. High-Intensity Interval Training for Individuals With Isolated Impaired Fasting Glucose: Protocol for a Proof-of-Concept Randomized Controlled Trial. JMIR Res Protoc. 2025 Feb 20;14:e59842. doi: 10.2196/59842.

Reference Type: DERIVED

PMID: 39977858 (View on PubMed)

Other Identifiers

UL1TR002378

Identifier Type: NIH

Identifier Source: secondary_id

View Link

STUDY00005855

Identifier Type: -

Identifier Source: org_study_id