Sepsis-induced changes in in vivo insulin action in diabetic rats

The present study examined whether sepsis exacerbates the diabetes-induced peripheral and hepatic insulin resistance. Vascular catheters were placed in diabetic (70 mg/kg streptozotocin, 4-wk duration) and nondiabetic rats, and sepsis was produced by subcutaneous injections of live Escherichia coli. Basal glucose metabolism was determined with the use of [3-3H]glucose initiated 18 h after the first injection of bacteria. Thereafter, in vivo insulin action was assessed with the use of the euglycemic hyperinsulinemic clamp technique. Sepsis in nondiabetic rats produced a 57% reduction in the maximal responsiveness for the insulin-induced increase in total glucose utilization compared with nondiabetic nonseptic animals. Diabetes alone decreased both insulin sensitivity and responsiveness. When the septic insult was superimposed on the diabetic condition, the maximum responsiveness was unchanged compared with non-septic diabetic rats, but the 50% maximally efficient dose was reduced from 817 to 190 microU/ml, suggesting an improvement in insulin sensitivity. Sepsis did not alter the insulin-induced suppression of hepatic glucose output in either nondiabetic or diabetic animals. Sepsis increased the plasma concentrations of epinephrine, norepinephrine, glucagon, and corticosterone in both nondiabetic and diabetic rats; however, the elevation in catecholamines and glucagon was 65 to 250% greater in the diabetic animals. These results indicate that hypermetabolic sepsis produces peripheral insulin resistance in nondiabetic rats but does not worsen the preexisting insulin resistance in diabetic animals, despite the higher prevailing blood levels of glucagon and catecholamines.