Intensity of peri-operative glycemic control and postoperative outcomes in patients with diabetes: a meta-analysis

Abstract

Aims

Peri-operative hyperglycemia is a risk factor for postoperative morbidity and mortality. However, the role of specific glycemic targets in reducing this risk has not been defined, particularly among patients with diabetes. Thus, our objective was to conduct a meta-analysis relating distinct peri-operative glycemic targets and postoperative outcomes in patients with diabetes.

Methods

A systematic review was performed by two authors utilizing pre-specified terms: “diabetes mellitus” and “perioperative” and “mortality” and “blood glucose” or “strict glucose control” or “intensive insulin therapy” in PUBMED, CENTRAL and EMBASE. Glycemic control was considered strict when perioperative targets ranged between 100 and 150 mg/dL (5.6–8.3 mmol/l), moderate when the targets ranged between 150 and 200 mg/dL 8.3–11.1 mmol/l), and liberal when the target was >200 mg/dL (11.1 mmol/l). The data were combined utilizing the Dersimoan–Laird random-effects method. The primary endpoint was postoperative mortality with secondary endpoints of postoperative atrial fibrillation, wound infection, and stroke.

Results

The literature search yielded 760 studies, of which only 6 met inclusion criteria. When compared with a liberal target, pooled data showed that a moderate glycemic target was associated with reduced postoperative mortality (OR = 0.48, 95% CI 0.24–0.76) and stroke (OR = 0.61, 95% CI 0.38–0.98), but no differences in atrial fibrillation or wound infection were found. There were no significant differences in postoperative outcomes between moderate versus strict perioperative glycemic target.

Conclusions

Pooled results suggest that in patients with diabetes, a moderate peri-operative glycemic target (150–200 mg/dl [5.6–8.3 mmol/l]) is associated with reduction in postoperative mortality and stroke compared with a liberal target (>200 mg/dl [11.1 mmol/l]), whereas no significant additional benefit was found with more strict glycemic control (<150 mg/dl [5.6 mmol/l]).

Introduction

Peri-operative hyperglycemia has been associated with increased ventilator dependence, atrial fibrillation, wound infection and mortality [1], [2]. Despite its clinical significance, the optimal perioperative glycemic targets for patients with diabetes are still uncertain. Most trials that informed the current American Diabetes Association guidelines for inpatient glycemic targets are based largely on critically ill patients who might or might not have undergone surgery [3], [4], [5]. Moreover, these trials included patients with and without diabetes [3], [6]. Given the potential differences in mortality risk and hyperglycemia treatment strategies [6], it would be hard to assume that peri-operative glycemic management will have the same effect in the population with and without diabetes prior to a rigorous investigation [7], [8]. In fact, studies have found insulin therapy to provide greater mortality reduction in patients without diabetes [7], [8], while Szekely et al. noted that deleterious effects from hyperglycemia were not observed in patients with diabetes unless the blood glucose (BG) was >300 mg/dL [8].

Moreover, individual studies that have addressed the effects of hyperglycemia treatment in surgical patients with diabetes have small enrollments and have yielded conflicting results [9], [10], [11], [12], [13], [14]. Given the lack of well-powered trials in patients with diabetes undergoing surgery that support current guideline recommendations and the conflicting results of individual studies, we conducted the following meta-analysis. Our objective was to analyze the current available evidence and relate distinct strategies of perioperative glycemic control and postoperative outcomes in patients with diabetes undergoing surgery.