To evaluate three evening insulin glargine dosing strategies for achievement of target (100–179 mg/dL; 5.5 - 9.8 mmol/L) and widened (80–249 mg/dL; 4.4 - 13.7 mmol/L) preoperative fasting blood glucose (FBG) ranges on the day of surgery.

Prospective, randomized, open trial.

Preoperative units at two sites of a suburban hospital system.

401 adult, ASA physical status 3 and 4 patients with type 1 and type 2 diabetes, undergoing elective noncardiac surgery.

Patients were divided into two groups according to absence of daily rapid-acting/short-acting insulin (insulin glargine-only group) or presence of daily rapid-acting/short-acting insulin (insulin glargine plus bolus group). Subjects were then randomized to three evening insulin glargine dosing strategies: (a) take 80% of usual dose, (b) call physician for dose, or (c) refer to dosing table, based on self-reported usual FBG and insulin regimen. In the prehospital setting, patients administered the instructed insulin glargine dose on the evening before surgery.

Venous blood glucose values were recorded in the preoperative holding area on the day of surgery.

No significant differences in target preoperative FBG achievement were detected among strategies in the insulin glargine-only group (n = 174) or the insulin glargine plus bolus group (n = 227). In widened preoperative FBG achievement, no significant difference was noted among strategies in the insulin glargine-only group. In the insulin glargine plus bolus group, fewer subjects following the dosing table had FBG > 249 mg/dL (> 13.7 mmol/L; P = 0.031).

Target preoperative FBG achievement was similar among strategies in both insulin glargine groups. An insulin glargine adjustment strategy based on usual glycemic control may better prevent severe preoperative hyperglycemia in patients receiving basal/bolus regimens.