Risk Factors for Preoperative Hyperglycemia in Surgical Patients with Diabetes: A Case-Control Study.

Background: Patients with diabetes are more likely to undergo a surgical procedure than the rest of the population, and it is well established that preoperative hyperglycemia is associated with adverse surgical outcomes. However, it is currently unknown what factors increase the odds of preoperative hyperglycemia in people with diabetes.

Objective: To identify patient characteristics that increase the risk of preoperative hyperglycemia.

Methods: This retrospective case-control study compared 100 patients with preoperative hyperglycemia on admission for elective surgery at South Health Campus in Calgary, Alberta (blood glucose > 10.9 mmol/L) with 200 controls who did not have preoperative hyperglycemia on admission for elective surgery (blood glucose ≤ 10.9 mmol/L). Multivariate logistic regression was used to identify risk factors for preoperative hyperglycemia.

Results: In the univariate analysis, age, number of comorbidities, increasing glycated hemoglobin (HbA_1c), type of diabetes, type of procedure, and diabetes medications (non-insulin, insulin, both, or none) were associated with increased odds of preoperative hyperglycemia (p < 0.05). However, in the adjusted analysis, only increasing HbA_1c (odds ratio [OR] 1.69, 95% confidence interval [CI] 1.36-2.12) and type 1 diabetes (OR 4.24, 95% CI 1.11-16.21, relative to type 2 diabetes) were associated with preoperative hyperglycemia.

Conclusions: These results can help clinicians to identify patients who may be at increased risk of hyperglycemia before an elective procedure. They also allow for treatment of those who would benefit most from additional guidance with regard to preoperative glucose management.