An observational cohort study to assess glycosylated hemoglobin screening for elective surgical patients

Uncontrolled blood glucose is associated with a higher incidence of surgical site infections, greater utilization of resources, and increased mortality. Preoperative screening for diabetes in elective surgical patients is not routinely performed. The purpose of this study was to examine blood glucose control in a preoperative surgical population.

Following ethics approval, adults presenting to the pre-surgical screening clinic in preparation for elective surgery were recruited. Data collection included a self-administered questionnaire on diabetic risk factors and blood glucose testing, including glycosylated hemoglobin (HbA1c). Descriptive analyses were conducted.

Seventy of the 402 participants (17.4%) had a previous diagnosis of diabetes (diabetics). Among those without a history of diabetes (n = 332 non-diabetics), 23.2% (n = 77) were considered very high risk for diabetes (HbA1c = 6.0-6.4%), and 3.9% (n = 13) had a provisional diagnosis of diabetes (HbA1c ≥ 6.5%). Fifty-six percent (n = 39/70) of diabetics had suboptimal glycemic control (HbA1c > 7.0%), and 51.3% (n = 20/39) of this subgroup presumed their blood sugars were reasonably or very well controlled. Fifteen percent (n = 2/13) of patients with a provisional diagnosis of diabetes (HbA1c ≥ 6.5%) had an elevated random blood sugar (RBS) (≥ 11.1 mmol·L⁻¹), while 67% (n = 8/12) had an elevated fasting blood sugar (FBS) (≥ 7.0 mmol·L⁻¹). Forty-two percent (n = 16/38) of suboptimally controlled diabetics (HbA1c > 7.0%) had an elevated RBS (≥ 11.1 mmol·L⁻¹), and 86% (n = 31/36) had an elevated FBS (≥ 7.0 mmol·L⁻¹).

Many elective surgical patients are at risk for unrecognized postoperative hyperglycemia and associated adverse outcomes. Random blood sugar testing has limited value and HbA1c may be a more appropriate test for the preoperative assessment of diabetic patients.