Intensive blood glucose control in acute and prolonged critical illness: endogenous secretion contributes more to plasma insulin than exogenous insulin infusion.

We investigated the contribution of impaired insulin secretion (observed as dynamics of C-peptide) and insulin resistance (measured by euglycemic clamps) to glucose dysregulation in 20 critically ill patients after severe trauma during feeding and intensive glucose control with intravenous insulin. Between the fourth and seventh day when insulin sensitivity is lowest, insulin secretion is highest and supranormal despite tight control of blood glucose by exogenous insulin. Afterward, plasma C-peptide decreases together with an improvement in insulin sensitivity. Multiple regression analysis revealed that plasma insulin is determined more by endogenous secretion than insulin infusion, even during the acute phase when exogenous insulin requirements are high.