Intracellular Counter-regulatory Mechanisms Following Low Blood Glucose

Study Overview
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Brief Summary
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Diabetes mellitus type I (DMI) is characterized by lack of endogenous insulin and these patients are 100% dependent on insulin substitution to survive. Diabetes mellitus type II (DMII) is characterized by reduced insulin sensitivity and sometimes also reduced insulin production, thus patients with DMII might also be dependent on insulin substitution. Insulin is produced in- and secreted from the pancreas when blood glucose concentration rises during- and after a meal. Insulin increases cellular uptake of glucose leading to lower blood glucose concentration. Substitution with insulin is/can be necessary in DM, but at the same time it induces the risk of hypoglycemia. This makes treatment with insulin a balancing act between hyper- and hypoglycemia. A hypoglycemic episode is a dreaded consequence of insulin overdosing, and also a very frequent reason for hospital admission in patients with DM. Examples of hypoglycemic symptoms may be; shaking, a sense of hunger, sweating, irritability progressing to lack of relevant cerebral responses and eventually coma, convulsions and possibly death. People with diabetes lose the ability to sense of low blood glucose with time, because of a lack of appropriate counter-regulatory responses, hereby increasing the risk of severe hypoglycemia. Understanding normal physiologic counter regulatory mechanisms during hypoglycemia is of major importance to patients with DM and has the potential to change medical treatment in diabetes, to reduce the risk of hypoglycemia. Hypothesis: Hypoglycemia counteracts insulin signaling via hormone-dependent intracellular counter-regulatory mechanisms, involving phosphorylation of specific signaling proteins. Aim: To define counter-regulatory mechanisms in muscle- and fat tissue during hypoglycemia, and to investigate the effect of insulin on lipid metabolism in healthy- and type I diabetic subjects.

Official Title
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Intracellular Counter-regulatory Mechanisms Following Low Blood Glucose

Conditions
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Diabetes Mellitus Type I, Hypoglycemia

Intervention / Treatment
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* Drug: Insulin (Insuman Rapid)
* Drug: Glucose
* Other: Saline


Participation Criteria
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Eligibility Criteria
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BMI > 19 and < 26 Written Consent Exclusion Criteria: Epilepsy Cardiac arrythmia Ischemic heart disease Other medical illness

Ages Eligible for Study
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Minimum Age: 18 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: Factorial Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Control<br>No insulin administered. Instead of insulin infusion, a small amount of saline is administered to keep the subject blinded. Three muscle biopsies and two fat biopsies will be obtained. A palmitic acid tracer will be given to estimate fatty acid metabolism. Forearm pletysmography will be performed twice. | Other: Saline<br> <br> |
| Experimental: Insulin<br>Insulin (Insuman Rapid) is administered once as a bolus of 0,1 IU/kg. Three muscle biopsies and two fat biopsies will be obtained. A palmitic acid tracer will be given to estimate fatty acid metabolism Forearm pletysmography will be performed twice | Drug: Insulin (Insuman Rapid)<br> <br> |
| Experimental: Insulin and glucose<br>Insulin (Insuman rapid) is administered once as a bolus injection of 0,1 IU/kg and glucose is given at the same time to avoid hypoglycemia in this arm. Three muscle biopsies and to fat biopsies is obtained. A palmitic acid tracer is given to estimate fatty acid metabolism Forearm pletysmography will be performed twice | Drug: Insulin (Insuman Rapid)<br> <br> Drug: Glucose<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Insulin and growth hormone signalling, expressed as CHANGE in phosphorylation of intracellular target proteins and mRNA expression of target genes in muscle- and fat-tissue. | Change in phosphorylation of target proteins and mRNA expression of target genes assessed with western blotting technique. | Biopsies obtained on each study day (arm). Muscle biopsies: time (t)= -30min, t= 30min and t= 75min. Fat biopsies: t= 30min and t= 75min | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intracellular markers of lipid metabolism in muscle- and fat tissue biopsies. | Assessed by Western blotting. | Biopsies obtained on each study day (arm). Muscle biopsies: time (t)= -30min, t= 30min and t= 75min. Fat biopsies: t= 30min and t= 75min | 
| Metabolism. | Assessment of glucose metabolism by forearm pletysmography and heated hand technique (duration of pletysmography = 30 min.) | measured twice on each study day (arm) at t= -30-0 min. and t= 50-80 min. | 
| Ghrelin |  | Measured at t = -30min., t=0min, t=15min, t= 30min., t=45min., t=60min., t= 75min., t=90min. and t=105min. on each study day (arm) | 
| Metabolism | A palmitic acid tracer will be given once per trial day to estimate fatty acid metabolism. Duration 1 hour. | once per study day (arm): t 45min - 105min. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Diabetes Mellitus Type I, Hypoglycemia, Counter-regulatory mechanisms