Postoperative tight glycemic control significantly reduces postoperative infection rates in patients undergoing surgery: a meta-analysis

Background: The benefit results of postoperative tight glycemic control (TGC) were controversial and there was a lack of well-powered studies that support current guideline recommendations. Methods: The EMBASE, MEDLINE, and the Cochrane Library databases were searched utilizing the key words "Blood Glucose", "insulin" and "Postoperative Period" to retrieve all randomized controlled trials evaluating the benefits of postoperative TGC as compared to conventional glycemic control (CGC) in patients undergoing surgery. Results: Fifteen studies involving 5053 patients were identified. As compared to CGC group, there were lower risks of total postoperative infection (9.4% vs. 15.8%; RR 0.586, 95% CI 0.504 to 0.680, p < 0.001) and wound infection (4. 6% vs. 7.2%; RR 0.620, 95% CI 0.422 to 0.910, p = 0.015) in TGC group. TGC also showed a lower risk of postoperative short-term mortality (3.8% vs. 5.4%; RR 0.692, 95% CI 0.527 to 0.909, p = 0.008), but sensitivity analyses showed that the result was mainly influenced by one study. The patients in the TGC group experienced a significant higher rate of postoperative hypoglycemia (22.3% vs. 11.0%; RR 3.145, 95% CI 1.928 to 5.131, p < 0.001) and severe hypoglycemia (2.8% vs. 0.7%; RR 3.821, 95% CI 1.796 to 8.127, p < 0.001) as compared to CGC group. TGC showed less length of ICU stay (SMD, -0.428 days; 95% CI, -0.833 to -0.022 days; p = 0.039). However, TGC showed a neutral effect on neurological dysfunction (1.1% vs. 2.4%; RR 0.499, 95% CI 0.219 to 1.137, p = 0.098), acute renal failure (3.3% vs. 5.4%, RR 0.610, 95% CI 0.359 to 1.038, p = 0.068), duration of mechanical ventilation (p = 0.201) and length of hospitalization (p = 0.082). Conclusions: TGC immediately after surgery significantly reduces total postoperative infection rates and short-term mortality. However, it might limit conclusion regarding the efficacy of TGC for short-term mortality in sensitivity analyses. The patients in the TGC group experienced a significant higher rate of postoperative hypoglycemia. This study may suggest that TGC should be administrated under close glucose monitoring in patients undergoing surgery, especially in those with high postoperative infection risk.