Contribution to postprandial hyperglycemia and effect on initial splanchnic glucose clearance of hepatic glucose cycling in glucose-intolerant or NIDDM patients.
Excessive amounts of glucose enter the systemic circulation when patients with non-insulin-dependent diabetes mellitus (NIDDM) eat a carbohydrate-containing meal. To determine the contribution of hepatic glucose cycling (defined as the net effect of glucose/glucose-6-phosphate cycling and uptake and release of glucose from hepatic glycogen) to postprandial hyperglycemia, diabetic, glucose-intolerant, and nondiabetic subjects were fed mixed meals. The meal contained both [2-3H]glucose (an isotope that is extensively detritiated during hepatic glucose cycling) and [6-3H]glucose (an isotope that is not detritiated during hepatic glucose cycling). Of the 50 g of carbohydrate contained in the meal, approximately 4-8 g underwent hepatic glucose cycling. Although total cycling of ingested glucose did not differ between diabetic, glucose-intolerant, and nondiabetic subjects (361 +/- 67 vs. 494 +/- 106 vs. 322 +/- 44 mumol.kg-1.5 h-1, respectively), the data suggested that hepatic cycling was increased in the diabetic and glucose-intolerant individuals but not in the nondiabetic subjects during the first 2 h after eating. Hepatic cycling during the first 2 h after eating was correlated with the prevailing glucagon concentration (r = 0.6, P less than 0.01) and increased (P less than 0.05) as hepatic glucose release increased. Hepatic glucose cycling had a marked effect on the measurement of so-called initial splanchnic glucose uptake. Nevertheless, however measured, initial splanchnic glucose uptake was not decreased and, if anything, was increased in diabetic and glucose-intolerant patients. Integrated postprandial hepatic glucose release increased (r less than 0.01) with the severity of fasting hyperglycemia.(ABSTRACT TRUNCATED AT 250 WORDS)
Butler
P C
PC
Department of Endocrinology and Internal Medicine, Mayo Clinic, Rochester, MN 55905.
Rizza
R A
RA
D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D004435:Eating; D005215:Fasting; D005260:Female; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000209:etiology*; D007328:Insulin / Q000097:blood; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D013152:Splanchnic Circulation; D013997:Time Factors
D001786:Blood Glucose; D007328:Insulin; D005934:Glucagon; D005947:Glucose