The Effect of Cold Exposure on Glucose Tolerance

Study Overview
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Brief Summary
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The purpose of the study is to evaluate the effect of cold exposure on an individual's glucose tolerance. Previous research has already shown that 10 days acclimation to a mild cold environment (14-15°C) can enhance insulin sensitivity. However, the duration in the cold environment was 6 hours per day which may not be practical for everyone. Therefore, the present study will investigate the effect of a shorter, and more intense cold exposure on an individual's glucose tolerance. It is hypothesised that cold exposure before consuming a glucose drink will enhance glucose clearance.

Official Title
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The Effect of Cold Exposure on the Glycaemic and Insulinaemic Responses to an Oral Glucose Load

Conditions
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Hyperglycemia

Intervention / Treatment
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* Other: Temperature


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria of healthy population: Signed informed consent. White European. Male. Age 18 - 40 years at the start of the study. BMI ≥ 20 and < 30 kg/m2. Exclusion Criteria of healthy population: Smoking. Active diseases (cardiovascular, diabetes mellitus, liver, kidney, cancer or other). Cold-acclimated (takes daily cold baths, works in a refrigerated environment, or regular cold water swimmer). Unstable body weight (gain or loss > 5kg in last 3 months). Currently undertaking a diet. Inclusion Criteria of prediabetes population: Signed informed consent. White European. Male or female. Women should be postmenopausal or use hormonal contraceptives. Age 30 - 75 years at the start of the study. BMI ≥ 25 and < 35 kg/m2. Generally healthy, no medication use that interferes with metabolism. If volunteers need medication (e.g. statin drugs, NSAIDs), it will be reviewed with the dependent physician on an individual basis. Impaired fasting glucose (5.6 mM to 6.9 mM) and/or blood glucose values 7.8-11.0 mM 2h after glucose drink consumption during OGTT in screening. Exclusion Criteria of prediabetes population: Smoking. Active diseases (cardiovascular, diabetes mellitus, liver, kidney, cancer or other). Cold-acclimated (takes daily cold baths, works in a refrigerated environment, or regular cold water swimmer). Unstable body weight (gain or loss > 5kg in last 3 months). Currently undertaking a diet.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: It is anticipated that 32 participants will enrol in the study. Specifically, 16 participants will be healthy individuals and the other 16 will be individuals with impaired fasting glucose (5.6 mM to 6.9 mM) and/or blood glucose values 7.8-11.0 mM 2h after glucose drink consumption during the OGTT in screening. Initially, the study will investigate the effect of the cold exposure on healthy individuals, and then depending on the results in these individuals, the intervention may be tested on participants with impaired glucose metabolism.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Cold exposure<br>Participants will be wrapped in a water-perfused suit. The temperature of the suit will be lowered to 10°C. From the onset of shivering, the participants will remain in the suit for 1 hour. | Other: Temperature<br>* Water-perfused suit.<br>|
| Other: Thermoneutral (Control)<br>Participants will be wrapped in a water-perfused suit. The temperature of the suit will remain at a thermoneutral temperature (32°C) to avoid shivering and excessive sweating. The duration will be matched to that during the cold exposure. | Other: Temperature<br>* Water-perfused suit.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glucose and insulin concentrations in response to an oral glucose load |  | 3 hours post glucose drink, measured 90 minutes after the cold exposure | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Energy expenditure measured using indirect calorimetry |  | 30 minutes before and during the 1 hour of cold exposure | 
| Core temperature measured using a telemetric pill |  | 30 minutes before and during the 1 hour of cold exposure | 
| Skin blood flow measured using laser doppler flowmetry |  | 30 minutes before and during the 1 hour of cold exposure | 
| Shivering activity assessed using surface electromyography |  | 30 minutes before and during the 1 hour of cold exposure | 
| Systolic and diastolic blood pressure measured using an automatic blood pressure device |  | 30 minutes before and during the 1 hour of cold exposure | 
| Thermal sensation | How warm or cold the participant perceives the environment. Assessed with a visual analogue scale (scale ranging from cold to hot). | 30 minutes before and during the 1 hour of cold exposure | 
| Skin temperature measured using iButtons |  | 30 minutes before and during the 1 hour of cold exposure | 
| Heart rate measured using chest heart rate monitor sensor |  | 30 minutes before and during the 1 hour of cold exposure | 
| Comfort | How comfortable or uncomfortable the participant perceives the environment. Comfort assessed with a visual analogue scale (scale ranging from very comfortable to very uncomfortable). | 30 minutes before and during the 1 hour of cold exposure | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cold Exposure, Glucose Tolerance