D-[U-11C]glucose uptake and metabolism in the brain of insulin-dependent diabetic subjects.
We used D-[U-11C]glucose to evaluate transport and metabolism of glucose in the brain in eight nondiabetic and six insulin-dependent diabetes mellitus (IDDM) subjects. IDDM subjects were treated by continuous subcutaneous insulin infusion. Blood glucose was regulated by a Biostator-controlled glucose infusion during a constant insulin infusion. D-[U-11C]-glucose was injected for positron emission tomography studies during normoglycemia as well as during moderate hypoglycemia [arterial plasma glucose 2.74 +/- 0.14 in nondiabetic and 2.80 +/- 0.26 mmol/l (means +/- SE) in IDDM subjects]. Levels of free insulin were constant and similar in both groups. The tracer data were analyzed using a three-compartment model with a fixed correction for 11CO2 egression. During normoglycemia the influx rate constant (k1) and blood-brain glucose flux did not differ between the two groups. During hypoglycemia k1 increased significantly and similarly in both groups (from 0.061 +/- 0.007 to 0.090 +/- 0.006 in nondiabetic and from 0.061 +/- 0.006 to 0.093 +/- 0.013 ml.g-1.min-1 in IDDM subjects). During normoglycemia the tracer-calculated metabolism of glucose was higher in the whole brain in the nondiabetic than in the diabetic subjects (22.0 +/- 1.9 vs. 15.6 +/- 1.1 mumol.100 g-1.min-1, P less than 0.01). During hypoglycemia tracer-calculated metabolism was decreased by 40% in nondiabetic subjects and by 28% in diabetic subjects. The results indicate that uptake of glucose is normal, but some aspect of glucose metabolism is abnormal in a group of well-controlled IDDM subjects.
Department of Endocrinology, Karolinska Hospital and Institute, Stockholm, Sweden.
M
M
Gutniak
G
G
Blomqvist
L
L
Widén
S
S
Stone-Elander
B
B
Hamberger
V
V
Grill
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001812:Blood-Brain Barrier; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002250:Carbon Radioisotopes; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007003:Hypoglycemia / Q000378:metabolism; D007328:Insulin / Q000627:therapeutic use; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D009928:Organ Specificity; D012016:Reference Values; D014055:Tomography, Emission-Computed
D001786:Blood Glucose; D002250:Carbon Radioisotopes; D007328:Insulin; D005947:Glucose