Hypoglycemia-induced increases in thalamic cerebral blood flow are blunted in subjects with type 1 diabetes and hypoglycemia unawareness.
The thalamus has been found to be activated during the early phase of moderate hypoglycemia. Here, we tested the hypothesis that this region is less activated during hypoglycemia in subjects with type 1 diabetes (T1DM) and hypoglycemia unawareness relative to controls. Twelve controls (5 F/7 M, age 40 ± 14 years, body mass index 24.2 ± 2.7 kg/m(2)) and eleven patients (7 F/4 M, age 39 ± 13 years, body mass index 26.5 ± 4.4 kg/m(2)) with well-controlled T1DM (A1c 6.8 ± 0.4%) underwent a two-step hyperinsulinemic (2.0 mU/kg per minute) clamp. Cerebral blood flow (CBF) weighted images were acquired using arterial spin labeling to monitor cerebral activation in the midbrain regions. Blood glucose was first held at 95 mg/dL and then allowed to decrease to 50 mg/dL. The CBF image acquisition during euglycemia and hypoglycemia began within a few minutes of when the target blood glucose values were reached. Hypoglycemia unaware T1DM subjects displayed blunting of the physiologic CBF increase that occurs in the thalamus of healthy individuals during the early phase of moderate hypoglycemia. A positive correlation was observed between thalamic response and epinephrine response to hypoglycemia, suggesting that this region may be involved in the coordination of the counter regulatory response to hypoglycemia.
Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota 55455, USA. mangia@umn.edu
Silvia
S
Mangia
Nolawit
N
Tesfaye
Federico
F
De Martino
Anjali F
AF
Kumar
Pete
P
Kollasch
Amir A
AA
Moheet
Lynn E
LE
Eberly
Elizabeth R
ER
Seaquist
D000293:Adolescent; D000328:Adult; D000368:Aged; D001364:Awareness; D001786:Blood Glucose / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism* / Q000503:physiopathology* / Q000523:psychology; D004837:Epinephrine / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D015309:Glucose Clamp Technique; D006728:Hormones / Q000502:physiology; D006801:Humans; D007003:Hypoglycemia / Q000378:metabolism* / Q000523:psychology; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013788:Thalamus / Q000098:blood supply*; D055815:Young Adult
D001786:Blood Glucose; D006728:Hormones; D005934:Glucagon; D004837:Epinephrine