Background and Goal of Study: Obese patients often develop postoperative hyperglycemia (1). Since the α2 agonist dexmedetomidine (Dex) reduces production of insulin (2), we examined the effect of Dex on postoperative glucose levels and insulin secretion pattern in obese patients with impaired glucose tolerance undergoing bariatric surgery.
Materials and methods: In a double-blind, prospective trial, 40 obese patients with impaired glucose tolerance, undergoing bariatric surgery, were randomized to receive Dex 1 ug/kg bolus and 0.5 ug/kg/h infusion during surgery (Dex Group; n=20) or placebo (Control Group; n=20). Patients were sampled for measuring baseline HgbA1c, glucose, insulin and subsequently glucose and insulin from onset of study drug infusion frequently for 12 h. Intraoperative fentanyl, postoperative morphine, pain, emesis and sedation level were recorded. Chi2 and mixed linear model, adjusted by glucose/insulin and HgbA1c were used for statistical analysis. A p value < 0.05 was considered statistically significant.
Results and discussion: There were no differences in demographic, intraoperative fentanyl, baseline HgbA1c, glucose and insulin, between groups. No significant changes were found in the intra and postoperative blood glucose levels between the groups (p=0.31 group*time interaction), without hyperglycemia. However, the interaction was significant for insulin secretion pattern (p=0.02). In the post hoc analysis, the effect of DEX on the slope of insulin curve, was significant from the 4th postoperative hour (Figure). While, there were no differences in PONV incidence, morphine consumption and pain, between groups, patients in the Dex Group were significantly more sedated during the first 6 postoperative hours.
Conclusion(s): Administration of Dex in obese patients with impaired glucose tolerance, undergoing bariatric surgery, produces a mismatch between the observed glucose level and the expected insulin secretion pattern without hyperglycemia.
This study does not support a sparing effect of Dex on intra and postoperative opioids.