Diabetes, Vol 39, Issue 4 501-507, Copyright © 1990 by American Diabetes Association
Effects of prolonged pulsatile hyperinsulinemia in humans. Enhancement of insulin sensitivity
GM Ward, JM Walters, PM Aitken, JD Best and FP Alford
Endocrine Unit, St. Vincent's Hospital, Fitzroy, Victoria, Australia.
Prolonged near-physiological pulsatile insulin infusion has a greater
hypoglycemic effect than continuous insulin infusion. We have previously
shown that continuous hyperinsulinemia induces insulin insensitivity. This
study examines the mechanisms responsible for the greater hypoglycemic
effect of pulsatile insulin administration, in particular, whether
prolonged pulsatile hyperinsulinemia induces insulin insensitivity. Basally
and 1 h after cessation of a 20-h pulsatile infusion of insulin (0.5
mU.kg-1.min-1), eight nondiabetic human subjects were assessed for 1)
glucose turnover with [3-3H]glucose, 2) insulin sensitivity by
minimal-model analysis of intravenous glucose tolerance tests, and 3)
monocyte insulin-receptor binding. The time-averaged plasma insulin levels
were 30 +/- 5 mU/L (mean +/- SE) during the infusion, which was similar to
the levels achieved in our previous continuous hyperinsulinemia study.
However, the average rate of glucose infusion to maintain euglycemia was
55% greater than in the previous study. Hepatic glucose production was -5.2
+/- 1.4 mumol.kg-1.min-1 during the infusion but returned to preinfusion
levels 1 h after the infusion was stopped. Insulin sensitivity (Sl) and
glucose tolerance (rate of glucose disappearance, Kg) showed changes
opposite in direction to our previous continuous hyperinsulinemia study
(pre- vs. postinfusion Kg 1.5 +/- 0.1 vs. 1.7 +/- 0.2 min-1 x 10(2), NS;
pre- vs. postinfusion Sl 8.4 +/- 2.3 vs. 11.8 +/- 3.7 min-1.mU-1.L x 10(4),
P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)