Measurement of Glucose/Glycogen Metabolism in Humans Using Magnetic Resonance at 4 or 7 Tesla
Condition: Type 1 Diabetes
MeSH terms: Diabetes Mellitus, Type 1
Study type: Interventional
Phase: Phase 2

Summary: 
      The long-range goal of this project is to determine the effects of diabetes and the
      hypoglycemic consequences of intensive therapy on in vivo brain glucose metabolism in humans.
      We will measure brain glycogen turnover and content in normal controls and subjects with
      diabetes under conditions of modest hyper-and hypoglycemia.
    

Detailed description: 
      On the morning before the study subjects will report to the Clinical Research Center and will
      be asked to stay at the Clinical Research Center for up to 72 hours. You will be asked not to
      eat anything after midnight. Small plastic catheters will be placed in two veins in subjects
      arms for infusion of glucose and for measuring blood glucose levels every 15-30 minutes.
      While subjects are in the study they will continuously receive a small dose of glucose
      enriched with 13C label either through the catheter or by drinking a small amount of a sugar
      water solution every 15-60 minutes. Subjects will be asked to transfer to the Center for
      Magnetic Resonance Research every 6-8 hours (except at night) where they will be asked each
      time to conduct an MRI scan as follows: Subjects will be placed on the patient bed in the
      magnet room for one-to-two hours. A nurse will stay with the subject at all times during this
      study. During some of the scans subjects may be asked to perform a visual task such as
      watching a changing checkerboard pattern through a mirror placed in front of their eyes.
      After each scan subjects will receive a low carbohydrate meal for weight-maintenance.

      Subjects may be asked to receive an infusion of glucose and/or insulin one-to-three times
      before and/or after the infusion of 13C-enriched glucose starts. During these infusions the
      subject's blood sugar will be maintained either higher or lower than normal levels for up to
      3 hours. This will be done to assess the effect of hyper- or hypoglycemia on brain glycogen
      metabolism.

      Subjects may also be asked several days prior to the study to report to the Clinical Research
      Center for a "mock" study to see if they are comfortable with the MRI scan and/or to test
      their body's response to either protocol (as described above, but carried out at the Clinical
      Research Center). If subjects would like to try the MRI procedure in advance, this test will
      not exceed 2 hours. If we need to test the subject's response to the infusion, this
      "pre-test" will involve only drawing blood and administering glucose and will be performed as
      described for either protocol above, but will last not more than 4 hours.

      Magnetic resonance measurements will be performed in the magnet and are very similar to
      magnetic resonance imaging exams (MRI). Subjects will always have the possibility to signal
      when they feel claustrophobic and wish to be removed from the magnet. The magnetic resonance
      measurements will be associated with a regular clunking noise that subjects may initially
      find unpleasant. For their comfort they will be offered to wear ear plugs. During the
      measurements in the magnet subjects will be asked to lie still for most of the time.
    

Intervention name(s): somatostatin
Intervention type(s): Drug
Intervention description(s): Somatostatin may be used to suppress endogenous insulin secretion
Intervention MeSH terms: Somatostatin
Allocation: Non-Randomized
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: Type 1 diabetes; Hypoglycemia unawareness