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

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.