Glucose-stimulated Pancreatic Islet and Intestinal Blood Flow in Healthy Subjects and in Type 1 Diabetes

Study Overview
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Brief Summary
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Type 1 diabetes is the major type of diabetes in the young. The pathophysiology still needs clarification in order to reach feasible means of preventing the disease. This study aims in defining the differences in pancreatic and intestinal blood flow between subjects with and without type 1 diabetes and validating the methodology to achieve this. Earlier animal studies have demonstrated changes in pancreatic islet blood flow using microspheres. The aim of this study is to test and validate a method for the assessment of islet perfusion in humans using molecular imaging. The investigators hypothesize that glucose-stimulated pancreatic perfusion is enhanced specifically in islets in healthy subjects and that this increase is mostly suppressed in subjects with type 1 diabetes. Positron emission tomography (PET) is a non-invasive imaging technique, which can be used to study flow and metabolism of different organs. Using radiowater ([15O]H2O) and PET, cellular perfusion can be measured directly and noninvasively. Recently, diffusion weighted magnetic resonance imaging (DWI) has also been applied as a complimentary method for the assessment to quantitate changes in pancreatic blood flow. In the study 10 healthy subjects and 10 subjects with type 1 diabetes will be imaged on two separate days. Pancreatic and intestinal perfusion are first measured with [15O]H2O and combined PET/magnetic resonance imaging before and 5 and 15 minutes after intravenous glucose infusion. On the second day, PET imaging is replaced by dynamic DWI conducted in the same time schedule and with intravenous glucose stimulation.

Official Title
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Glucose-stimulated Pancreatic Islet and Intestinal Blood Flow in Healthy Subjects and in Type 1 Diabetes Using Positron Emission Tomography and Diffusion Weighted Imaging

Conditions
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Type 1 Diabetes

Participation Criteria
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Eligibility Criteria
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Criteria for healthy subjects Inclusion criteria Healthy as judged by history and examination Age 18-30 years Body mass index (BMI) 18 - 27 kg/m2 Normal 2 h oral glucose tolerance test Exclusion criteria Any chronic disease Pregnancy Blood pressure > 140/90 mmHg Smoking Presence of any ferromagnetic objects in the body Any other condition that could possibly create a hazard to the subject safety, endanger the study procedures or interfere with the interpretation of the study results Criteria for subjects with type 1 diabetes (T1D) Inclusion criteria T1D diagnosed at least 5 years ago Age 18-30 years BMI 18 - 30 kg/m2 Good or moderate glycemic control with long-acting insulin analogue combined with injections of rapid-acting insulin Uncomplicated T1D or with minor microvascular complications Exclusion criteria Any other condition or disease possibly affecting circulation, as evaluated by a physician Pregnancy Blood pressure > 140/90 mmHg Smoking Presence of any ferromagnetic objects in the body Any other condition that could possibly create a hazard to the subject safety, endanger the study procedures or interfere with the interpretation of the study results

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Type 1 diabetes<br> | |
| Healthy subjects<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pancreatic islet blood flow acquired with PET and DWI (ml ml-1 min-1) | healthy subjects and subjects with T1DM are studied once using imaging | within one study day | 
| Intestinal blood flow acquired with PET and DWI (ml ml-1 min-1) | healthy subjects and subjects with T1DM are studied once using imaging | within one study day |