POSTOPERATIVE INSULIN-RESISTANCE AND CIRCULATING CONCENTRATIONS OF STRESS HORMONES AND CYTOKINES

Insulin sensitivity was determined before and after elective surgery i n 31 otherwise healthy patients undergoing elective surgery for open c holecystectomy (n = 24) or inguinal hernia repair (n = 7) and compared with concomitant plasma concentrations of stress hormones and cytokin es. Insulin sensitivity was determined employing the normoglycaemic, h yperinsulinaemic clamp at a plasma insulin concentration of 380 pmol/l and a blood glucose concentration of 4.5 mmol/l. Five of the patients undergoing cholecystectomy were studied again on days 5, 9 and 20 aft er surgery. Preoperative insulin sensitivity ranged from 2.2 to 14.3 m g/kg/min. All patients exhibited reduced insulin sensitivity on the fi rst postoperative day and the mean value fell from 4.7 (0.4) to 2.7 (0 .5) mg/kg/min. More pronounced reductions were found after cholecystec tomy. A significant increase was found in plasma concentrations of int erleukin-6 (IL-6) postoperatively as compared to preoperative values. However, no significant changes were seen in the postoperative plasma concentrations of any of the hormones studied in patients undergoing h ernia repair, while minor increments were seen in patients undergoing open cholecystectomy. There was a significant (r = 0.50, P = 0.005) li near relationship between the reduction in relative insulin sensitivit y and the concomitant plasma levels of IL-6. However, no such relation could be confirmed between the changes in plasma hormone concentratio ns (neither absolute nor relative changes) and the simultaneous altera tion in relative insulin sensitivity. In addition, after including thr ee patients who had undergone ileo-anal pouch construction surgery, th e relationship between postoperative insulin sensitivity and IL-6 leve ls was even stronger (r = 0.62, P = 0.001). These results suggest that the immunomodulating effects of endogenous IL-6 is of importance in t he acute response after surgery and are associated with the developmen t of insulin resistance, while simultaneous plasma concentrations of s tress hormones seem to be less sensitive markers of the degree of post operative metabolic disturbance.