title: Effect of loss of first-phase insulin secretion on hepatic glucose production and tissue glucose disposal in humans.
abstract: To examine the importance of first-phase insulin secretion on total body glucose homeostasis, six normal subjects (age, 24 +/- 1 yr; ideal body wt, 100 +/- 1%) received three hyperglycemic (+75 mg/100 ml) clamp studies in combination with [3-3H]glucose: study I, 150 min hyperglycemic clamp; study II, hyperglycemic clamp plus somatostatin (6 micrograms/min) plus basal glucagon replacement (0.4 ng.kg-1.min-1) plus an insulin infusion designed to mimic only the second phase of insulin secretion; and study III, hyperglycemic clamp plus somatostatin plus basal glucagon plus an insulin infusion designed to mimic both the first and second phase of insulin secretion. Basal plasma C-peptide concentrations averaged 0.21 +/- 0.01 pmol/ml in the three study protocols. In study I the plasma C-peptide response demonstrated an early burst within the first 10 min followed by a gradually increasing phase of C-peptide secretion that lasted until the end of the study. In studies II and III plasma C-peptide declined within the first 10 min after somatostatin was started and averaged 0.06 +/- 0.01 and 0.05 +/- 0.01 pmol/min, respectively. Basal hepatic glucose production (2.3 +/- 0.2 mg.kg-1.min-1) was suppressed by 90% at 20 min and remained suppressed thereafter in studies I and III. In contrast, in study II hepatic glucose production was inhibited by only 50% (1.1 +/- 0.2 mg.kg-1.min-1) at 60 min (P less than 0.01 vs. studies I and III) and remained incompletely suppressed even after 150 min.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Division of Diabetes, University of Texas Health Science Center, San Antonio 78284-7886.
authors.forename: L
authors.initials: L
authors.lastname: Luzi
authors.forename: R A
authors.initials: RA
authors.lastname: DeFronzo
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D002096:C-Peptide / Q000097:blood; D005260:Female; D005934:Glucagon / Q000494:pharmacology*; D005943:Gluconeogenesis; D005947:Glucose / Q000378:metabolism*; D015309:Glucose Clamp Technique; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007328:Insulin / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D000078790:Insulin Secretion; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D012016:Reference Values
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D005934:Glucagon; D005947:Glucose