Sympathetic Nerve Activity During Hypoglycemia and Exercise

Study Overview
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Brief Summary
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The purpose of this study is to determine if either hypoglycemia or exercise cause differential responses in muscle and skin sympathetic nerve activity.

Detailed Description
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The body has defensive responses to correct low blood sugar (hypoglycemia). A vital component of this response is release of glucagon and activation of the sympathetic nervous system, which provides the means for raising blood glucose levels towards normal. We can measure circulating hormones indicating the level of these responses, but additionally, sympathetic nervous system responses can be measured directly. We can measure the sympathetic nerve activity that controls blood flow to muscles (MSNA) and blood flow and sweating to skin (SSNA). The purpose of this study is to determine if either hypoglycemia or exercise cause differential responses in muscle and skin sympathetic nerve activity. We would also like to determine what the sympathetic response is to cycling exercise with insulin and normal blood sugar. Therefore, we would like to test the sympathetic responses to insulin with normal blood glucose, hypoglycemia, and during exercise bouts and normal blood glucose, with or without insulin.

Official Title
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Sympathetic Nerve Activity During Hypoglycemia and Exercise

Conditions
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Diabetes Mellitus

Intervention / Treatment
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* Procedure: Hyperinsulinemic glucose clamp procedures
* Procedure: moderate exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 36 Healthy male and female subjects (18 males and 18 females) aged 18-40 yr All potential volunteers will have routine blood test to screen for hepatic, renal, and hematological abnormalities Body mass index ≤30kg · m-2 Normal bedside autonomic function Female volunteers of childbearing potential will undergo HCG pregnancy test at screening and again on the study day. Exclusion Criteria: Pregnant women Subjects unable to give voluntary informed consent Subjects on anticoagulant drugs or anemic Subjects with a recent medical illness Subjects with a history of hypertension, heart disease or cerebrovascular disease Subjects with known liver or kidney disease Subjects with recent weight loss or consuming a low carbohydrate diet

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 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

Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>Hyperinsulinemic euglycemic or hypoglycemic clamp with Muscle and skin sympathetic nerve activity recording in arm and/or leg | Procedure: Hyperinsulinemic glucose clamp procedures<br>* 2 hours of either euglycemic or hypoglycemic glucose clamping<br>|
| Experimental: 2<br>Exercise with insulin or no insulin infused with muscle and skin sympathetic nerve activity measurements | Procedure: moderate exercise<br>* 90 minutes of moderate exercise with either hyperinsulinemia or euinsulinemia<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Muscle sympathetic nerve activity |  | 2 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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exercise, hypoglycemia, sympathetic nerve activity