Underestimation of glucose turnover measured with (6-/sup 3/H)- and (6,6-/sup 2/H)- but not (6-/sup 14/C)glucose during hyperinsulinemia in humans
Recent studies indicate that hydrogen-labeled glucose tracers underestimate glucose turnover in humans under conditions of high flux. The cause of this underestimation is unknown. To determine whether the error is time-, pool-, model-, or insulin-dependent, glucose turnover was measured simultaneously with (6-3H)-, (6,6-2H2)-, and (6-14C)glucose during a 7-h infusion of either insulin (1 mU.kg-1.min-1) or saline. During the insulin infusion, steady-state glucose turnover measured with both (6-3H)glucose (8.0 +/- 0.5 mg.kg-1.min-1) and (6,6-2H2)glucose (7.6 +/- 0.5 mg.kg-1.min-1) was lower (P less than .01) than either the glucose infusion rate required to maintain euglycemia (9.8 +/- 0.7 mg.kg-1.min-1) or glucose turnover determined with (6-14C)glucose and corrected for Cori cycle activity (9.8 +/- 0.7 mg.kg-1.min-1). Consequently negative glucose production rates (P less than .01) were obtained with either (6-3H)- or (6,6-2H2)- but not (6-14C)glucose. The difference between turnover estimated with (6-3H)glucose and actual glucose disposal (or 14C glucose flux) did not decrease with time and was not dependent on duration of isotope infusion. During saline infusion, estimates of glucose turnover were similar regardless of the glucose tracer used. High-performance liquid chromatography of the radioactive glucose tracer and plasma revealed the presence of a tritiated nonglucose contaminant. Although the contaminant represented only 1.5% of the radioactivity in the (6-3H)glucose infusate, its clearance was 10-fold less (P less than .001) than that of (6-3H)glucose. This resulted in accumulation in plasma, with the contaminant accounting for 16.6 +/- 2.09 and 10.8 +/- 0.9% of what customarily is assumed to be plasma glucose radioactivity during the insulin or saline infusion, respectively (P less than .01).
- Research Organization:
- Mayo Clinic, Rochester, MN (USA)
- OSTI ID:
- 6442571
- Journal Information:
- Diabetes; (United States), Vol. 38:1
- Country of Publication:
- United States
- Language:
- English
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GLUCOSE
METABOLISM
METABOLIC DISEASES
PATHOGENESIS
CARBON 14 COMPOUNDS
DEUTERIUM
INSULIN
LIQUID COLUMN CHROMATOGRAPHY
TRITIUM COMPOUNDS
ALDEHYDES
CARBOHYDRATES
CHROMATOGRAPHY
DISEASES
HEXOSES
HORMONES
HYDROGEN ISOTOPES
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MONOSACCHARIDES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
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550901* - Pathology- Tracer Techniques