A client who has type 2 diabetes mellitus takes metformin 500 mg PO daily for blood glucose control. The client has been NPO since midnight in preparation for general anesthesia and surgery. At 0700 the client's serum glucose level is 250 mg/dL (13.9 mmol/L). Which action should the nurse implement? Reference Range: Fasting Blood Glucose [74 to 106 mg/dL (4.1 to 5.9 mmol/L)]

Rationale: A. Obtain a prescription for regular insulin subcutaneous per sliding scale: The most appropriate intervention is to use short-acting insulin under provider direction. Sliding scale insulin allows for effective and adjustable glucose control before surgery without increasing the risk of lactic acidosis associated with metformin. B. Administer the client’s daily metformin tablet with a sip of water: Metformin is contraindicated when clients are NPO and undergoing anesthesia because it increases the risk of lactic acidosis, particularly in situations involving altered renal perfusion. C. Record the blood glucose results and requisition a repeat test in one hour: Simply recording and retesting delays needed intervention for hyperglycemia. The client’s glucose level is significantly above the normal fasting range, requiring immediate management. D. Prepare to initiate a continuous IV infusion of insulin in normal saline: Continuous IV insulin infusions are typically reserved for critically ill or unstable patients, such as those with diabetic ketoacidosis or in intensive care settings. In this stable preoperative client, subcutaneous regular insulin is the appropriate first-line option.