The Influence of Sampling Site When Assessing Glucose Tolerance or Insulin Sensitivity With Oral Glucose Ingestion

Study Overview
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Brief Summary
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For decades, it has been known that post-meal blood glucose concentrations were associated with the risk of T2D, which was reflected in early diagnostic guidelines. The oral glucose tolerance test (OGTT) has been used since at least 1923 and has remained the most common test for assessing glucose tolerance. Arterial blood (or arterialised blood using heated hand technique) is most appropriate for determining glucose tolerance and insulin sensitivity since this best represents the concentrations of metabolites and hormones that peripheral tissues are exposed to. It is essential to investigate whether venous blood (sometimes used during an OGTT) is representative of arterialised blood during an OGTT, and under different metabolic conditions. The investigators want to understand whether OGTT-derived insulin sensitivity indices differ from venous and arterialised blood; and 2) investigate whether metabolic status (i.e. rest vs lower-limb exercise) influences the difference between forearm venous and arterialised concentrations of glucose and insulin during an OGTT.

Official Title
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The Influence of Sampling Site When Assessing Glucose Tolerance or Insulin Sensitivity With Oral Glucose Ingestion

Conditions
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Hyperglycemia, Insulin Sensitivity

Intervention / Treatment
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* Behavioral: Rest
* Behavioral: Exercise
* Other: Dorsal Hand Vein Cannulation (heated hand technique)
* Other: Venous Cannulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 18-49 years Able and willing to safely comply with all study procedures Able to provide written informed consent for participation Exclusion Criteria: Diagnosis of any bleeding disorder or taking medication which impacts blood coagulation The presence of any contraindications to maximal exercise testing, as determined using a physical activity readiness questionnaire (PAR-Q). Any diagnosis of metabolic disease (i.e. cardiovascular disease or type 2 diabetes).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 49 Years

Sexes Eligible for Study
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Male

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: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Rest<br>Remain rested prior to the oral glucose tolerance test | Behavioral: Rest<br>* Allowed to watch television or read for one hour prior to oral glucose tolerance test<br>Other: Dorsal Hand Vein Cannulation (heated hand technique)<br> <br> Other: Venous Cannulation<br> <br> |
| Experimental: Exercise<br>Complete exercise prior to the oral glucose tolerance test | Behavioral: Exercise<br>* One hour of cycling at 50% of maximal power output<br>Other: Dorsal Hand Vein Cannulation (heated hand technique)<br> <br> Other: Venous Cannulation<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Postprandial plasma glucose concentrations (area under the concentration-time curve) |  | 120 mins | 
| OGTT-derived insulin sensitivity |  | 120 mins | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fasting plasma glucose concentrations |  | 5 mins | 
| Fasting plasma insulin concentrations |  | 5 mins | 
| Fasting plasma lactate concentrations |  | 5 mins | 
| Fasting plasma triglyceride concentrations |  | 5 mins | 
| Postprandial plasma lactate concentrations (area under the concentration-time curve) |  | 120 mins | 
| Postprandial plasma triglyceride concentrations (area under the concentration-time curve) |  | 120 mins | 
| Substrate utilization for energy provision |  | 180 mins | 
| Postprandial plasma insulin concentrations (area under the concentration-time curve) |  | 120 mins |