Diabetes Care, Vol 10, Issue 3 293-299, Copyright © 1987 by American Diabetes Association
Biphasic patterns of peripheral insulin and glucose levels after lunch in normal subjects
DC Robbins, J Jaspan, B Vasquez and E Van Cauter
The dynamic relationship of glucose concentrations and insulin secretion
during the postabsorptive state is complex and has been associated with a
variety of cyclic rhythms. To study the pattern of insulin and glucose
response immediately after a mixed meal, we collected blood every 15 min
from 0730 to 1645 h from eight normal resting men (age 24.9 +/- 2.1 yr).
They took identically constituted mixed meals at 0800 and 1145 h.
Concentrations of glucose and insulin were measured in samples taken
throughout the study, whereas levels of C-peptide, glucagon, and alpha-NH2
were determined in samples taken after 1130 h only. Computer-assisted
analysis was used to identify significant increments and declines in
concentrations and to quantify the coincidence of peaks of glucose,
C-peptide, glucagon, and alpha-NH2 with peaks of insulin. Coefficients of
correlation between data points were calculated for each individual. The
patterns of blood insulin and glucose after breakfast and lunch were
different. After breakfast, a single simultaneous peak in insulin and
glucose occurred approximately 60 min after starting the meal. In contrast,
the pattern after lunch in seven of the eight subjects was clearly
biphasic. There were secondary, significant coincident peaks in serum
insulin, glucose, and C-peptide occurring 1.75-2.25 h after the meal was
served. The secondary peak appeared unrelated to the late absorption of
protein because it was not associated with consistent changes in serum
alpha-NH2 concentration. Erratic variations characterized the postlunch
pattern of glucagon levels, excluding a role for this counterregulatory
hormone in the control of the biphasic insulin and glucose
response.(ABSTRACT TRUNCATED AT 250 WORDS)