title: Regional brain activation during hypoglycemia in type 1 diabetes.
abstract: BACKGROUND
  Mechanisms underlying the brain response to hypoglycemia are not well understood.
  
  
  OBJECTIVE
  Our objective was to determine the blood glucose level at which the hypothalamus and other brain regions are activated in response to hypoglycemia in type 1 diabetic patients and control subjects.
  
  
  METHODS
  This was a cross-sectional study evaluating brain activity using functional magnetic resonance imaging in conjunction with a hyperinsulinemic hypoglycemic clamp to lower glucose from euglycemia (90 mg/dl) to hypoglycemia (50 mg/dl).
  
  
  METHODS
  The study was performed at the Brain Imaging Center in the McLean Hospital.
  
  
  METHODS
  Seven type 1 diabetic patients between 18 and 50 yr old and six matched control subjects were included in the study.
  
  
  METHODS
  Hyperinsulinemic hypoglycemic clamp was performed.
  
  
  METHODS
  Blood glucose level at peak hypothalamic activation, amount of regional brain activity during hypoglycemia in both groups, and difference in regional brain activation between groups were calculated.
  
  
  RESULTS
  The hypothalamic region activates at 68 +/- 9 mg/dl in control subjects and 76 +/- 8 mg/dl in diabetic patients during hypoglycemia induction. Brainstem, anterior cingulate cortex, uncus, and putamen were activated in both groups (P < 0.001). Each group also activated unique brain areas not active in the other group.
  
  
  CONCLUSIONS
  This application of functional magnetic resonance imaging can be used to identify the glucose level at which the hypothalamus is triggered in response to hypoglycemia and whether this threshold differs across patient populations. This study suggests that a core network of brain regions is recruited during hypoglycemia in both diabetic patients and control subjects.
authors.affiliation: Research Division, Joslin Diabetes Center, 1 Joslin Place Room 350, Boston, Massachusetts 02215, USA. gail.musen@joslin.harvard.edu
authors.forename: Gail
authors.initials: G
authors.lastname: Musen
authors.forename: Donald C
authors.initials: DC
authors.lastname: Simonson
authors.forename: Nicolas R
authors.initials: NR
authors.lastname: Bolo
authors.forename: Amy
authors.initials: A
authors.lastname: Driscoll
authors.forename: Katie
authors.initials: K
authors.lastname: Weinger
authors.forename: Annaswamy
authors.initials: A
authors.lastname: Raji
authors.forename: Jean
authors.initials: J
authors.lastname: Théberge
authors.forename: Perry F
authors.initials: PF
authors.lastname: Renshaw
authors.forename: Alan M
authors.initials: AM
authors.lastname: Jacobson
mesh_terms: D000328:Adult; D000367:Age Factors; D001786:Blood Glucose / Q000032:analysis; D001921:Brain / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007003:Hypoglycemia / Q000503:physiopathology*; D007031:Hypothalamus / Q000502:physiology; D008297:Male; D008875:Middle Aged
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human