Sd. Wise et al., OVERNIGHT NORMALIZATION OF GLUCOSE-CONCENTRATIONS IMPROVES HEPATIC BUT NOT EXTRAHEPATIC INSULIN ACTION IN SUBJECTS WITH TYPE-2 DIABETES-MELLITUS, The Journal of clinical endocrinology and metabolism, 83(7), 1998, pp. 2461-2469
Subjects with poorly controlled type 2 diabetes are both hyperglycemic
and insulin resistant. To determine whether short term restoration of
normoglycemia improves insulin action, hyperinsulinemic (similar to 3
00 pmol/L) euglycemic clamps were performed in diabetic subjects after
either overnight infusion of saline or overnight infusion of insulin
in amounts sufficient to maintain euglycemia throughout the night. Fas
ting glucose concentrations (5.2 +/- 0.2 vs. 11.9 +/- 1.4 mmol/L; P <
0.01) and rates of endogenous glucose production (13.0 +/- 1.I us. 18.
6 +/- 1.6 mu mol/kg.min; P < 0.05) were both lower after overnight ins
ulin than overnight saline. Insulin-induced stimulation of glucose upt
ake (to 34.9 +/- 6.8 vs. 28.8 +/- 3.4 mu mol/kg.min; P = 0.2) and inhi
bition of free fatty acids (to 0.13 +/- 0.03 vs. 0.12 +/- 0.04 mmol/L;
P = 0.6) did not differ after overnight saline and overnight insulin.
In contrast, endogenous glucose production during the final hour of t
he hyperinsulinemic clamps (i.e. when glucose concentrations were the
same) remained higher (P = 0.05) after overnight saline than after ove
rnight insulin (5.5 +/- 1.5 us. 0.02 +/- 1.4 mu mol/kg min). Thus, acu
te restoration of euglycemia by means of an overnight insulin infusion
improves hepatic (and perhaps renal) but not extrahepatic insulin act
ion.