The Negative Impact of Insulin Therapy for Acute Hyperglycemia Secondary to Glucose Load on Plasma Amino Acid Profiles in a Rat Model of Sepsis

Abstract

Background: In critical illnesses, insulin therapy under overfed conditions with an excessive glucose infusion may cause metabolic disturbances in skeletal muscle mainly through muscle cell glucose uptake and the inhibition of physiological protein breakdown. The aim of this study was to examine the potential negative aspects of insulin therapy in a rat model of sepsis. Materials and Methods: Male Sprague-Dawley rats underwent cecal ligation and puncture (CLP) or sham surgery. A pre-established continuous intravenous glucose infusion was initiated immediately after surgery. Rats with sepsis were divided into four groups (n = 7 in each group) based on target blood glucose (BG) levels: a no glucose (NG) group (100-150 mg/dl), moderate glucose (MG) group (200-300 mg/dl), high glucose (HG) group (>300 mg/dl), and the hyperinsulinemia (HI) group, which received the same glucose infusion as the HG group with the insulin infusion (200-300 mg/dl). The sham group underwent sham surgery and received the same glucose infusion as the HG group. All rats were sacrificed 9 h after surgery, and blood samples were collected to measure plasma amino acid (AA) profiles. To examine survival rates in the 48 h following CLP, the HG, MG, and HI groups were newly prepared according to the aforementioned experimental design. Results: Plasma levels of the branched-chain AAs, glutamine, arginine, citrulline, and alanine among the septic groups slightly and inversely decreased with the amount of glucose infused, and HI had significantly lower values (p < 0.01). A strong correlation was observed among the AAs. Plasma 3-methylhistidine concentrations were the highest in the HI group. The survival rate of the HI group was greater than that of the HG, but did not reach the level of the MG group. Conclusion: In critical illnesses, insulin therapy under overfed conditions may impair the physiological supply of AAs and conditionally essential AA starvation, such as glutamine and arginine, and may have an adverse impact on the prognosis of patients.