The most appropriate management of this patient's insulin prior to surgery is to administer insulin glargine as usual and withhold the scheduled insulin lispro. Preoperative management of diabetes mellitus requires determination of the patient's medical regimen, recent glycemic control, stress/duration of surgery, and anticipated duration of periprocedural fasting. In most cases, long-acting insulins (glargine and detemir) should be continued uninterrupted at the same dose unless a patient has risk factors for hypoglycemia or is undergoing a procedure requiring a prolonged period without enteral nutrition. Conversely, scheduled short-acting insulins such as lispro should be withheld during the fasting state because their purpose is to suppress postprandial hyperglycemia. In this case, the patient does not require a prolonged procedure or extended period of fasting. He also has no risk factors for hypoglycemia, and his average glucose level is higher than goal. Therefore, continuation of long-acting insulin while withholding scheduled short-acting insulin affords the best approach to glycemic control in the immediate perioperative period.

Continuing insulin lispro along with insulin glargine increases the risk for hypoglycemia during the fasting state. Short-acting insulins should be withheld when a patient is not taking anything by mouth unless the patient requires correction doses for significant hyperglycemia (plasma glucose level >200 mg/dL [11.1 mmol/L]).

Continuous insulin infusion is usually reserved for patients with uncontrolled hyperglycemia, with metabolic acidosis, or who are undergoing high-risk procedures (such as cardiac surgery). This patient has an acceptable plasma glucose level and is undergoing intermediate-risk surgery.

No insulin therapy increases the risk of significant hyperglycemia in this patient under physiologic stress. Therefore, treatment is indicated to prevent significant increases in the plasma glucose level.