Diabetes, Vol 36, Issue 11 1230-1237, Copyright © 1987 by American Diabetes Association
In vivo regulation of non-insulin-mediated and insulin-mediated glucose uptake by cortisol
AD Baron, P Wallace and G Brechtel
Department of Medicine, Veterans Administration Medical Center, San Diego, CA 92161.
In vivo glucose uptake (Rd) occurs via two mechanisms: insulin-mediated
glucose uptake (IMGU), which occurs in insulin-sensitive tissues, and
non-insulin-mediated glucose uptake (NIMGU), which occurs in both
insulin-sensitive and non-insulin-sensitive tissues. To determine whether
these two pathways for in vivo glucose disposal are regulated
independently, we studied the effect of stress levels of cortisol on IMGU
and NIMGU in seven normal subjects after an overnight fast. To study NIMGU,
somatostatin (SRIF, 600 micrograms/h) was infused to suppress endogenous
insulin secretion and create severe insulinopenia, and glucose turnover was
measured isotopically while serum glucose was clamped at approximately 200
mg/dl for 240 min. Separate studies were performed during the overnight
infusion of saline or hydrocortisone (HCT; 2.0 micrograms.kg-1.min-1). The
final 120 min of each study were used for data analysis. Under these
conditions, insulin action is absent, and Rd = NIMGU. NIMGU was 204 +/- 11
mg/min and 208 +/- 8 mg/dl during saline and HCT, respectively (P NS).
Therefore, HCT did not modulate NIMGU. To measure the effect of cortisol on
Rd, hyperglycemic (200 mg/dl)-hyperinsulinemic clamp studies (30 mU.m-2.
min-1) were performed during the infusion of saline or HCT. The results
demonstrate that during saline infusion, steady-state rates of Rd (10.4 +/-
0.8 mg.kg-1.min-1) were achieved by 160 min; in contrast, during HCT
infusion, Rd never reached steady state but increased from 4.5 +/- 0.2 in
the 2nd h to 7.6 +/- 0.4 mg.kg-1.min-1 in the 4th h, P less than
.01.(ABSTRACT TRUNCATED AT 250 WORDS)