Diabetes, Vol 37, Issue 10 1351-1357, Copyright © 1988 by American Diabetes Association
Reduction of insulin clearance during hyperglycemic clamp. Dose-response study in normal humans
H Tillil, ET Shapiro, AH Rubenstein, JA Galloway and KS Polonsky
Department of Medicine, University of Chicago, Pritzker School of Medicine, Illinois.
Insulin secretion and clearance were studied in eight normal subjects who
underwent hyperglycemic clamp studies at plasma glucose levels of 120, 225,
and 300 mg/dl on three occasions. Insulin secretion rates were calculated
during a 1-h baseline period and during 3 h of glucose clamping from a
two-compartmental analysis of peripheral C-peptide concentrations with
individual kinetic parameters derived after intravenous bolus injections of
biosynthetic human C-peptide. At the 300-mg/dl clamp level, the insulin
secretion rate increased to a value 9.9 +/- 0.7 times that of basal at the
end of the clamp (mean +/- SE), whereas over the same period, the
peripheral insulin concentrations increased to a greater extent, reaching a
value 15.4 +/- 1.2 times that of basal (P = .002). This greater relative
increase in the insulin concentration in comparison with the corresponding
insulin secretion rate suggests a reduction in the clearance of endogenous
insulin. A similar trend was seen at the 225-mg/dl clamp level, but the
relative increase in the insulin concentration (9.9 +/- 1.5 times that of
basal) was not significantly higher than the relative increase in the
insulin secretion rate (8.1 +/- 0.5 times that of basal, P = .17). At the
120-mg/dl clamp level, the relative increases in the insulin secretion rate
(2.7 +/- 0.2 times that of basal) and the insulin concentration (2.4 +/-
0.2 times that of basal) were similar (P = .26), indicating no reduction in
endogenous insulin clearance during moderate stimulation of insulin
secretion. In conclusion, a reduction in endogenous insulin clearance
occurs during greater stimulation of insulin secretion at higher
glucose-clamp levels.(ABSTRACT TRUNCATED AT 250 WORDS)