What test should be ordered for a patient with type 2 diabetes (T2D), on metformin, with a Hemoglobin A1c (HbA1c) of 6.8, normal vital signs, and no significant medical history, who is undergoing ankle surgery?

Preoperative Testing for Ankle Surgery in a Patient with Type 2 Diabetes

No additional testing is required at this time—proceed with surgery while implementing appropriate perioperative glucose management. 1, 2

Rationale for Not Ordering Additional Tests

HbA1c is Acceptable for Elective Surgery

• This patient's HbA1c of 6.8% is well below the critical threshold of 8% that would mandate postponing elective surgery. 1, 2
• The American Diabetes Association specifically recommends an A1C goal of <8% for elective surgeries whenever possible, and this patient meets this criterion. 1
• The French Society of Anaesthesia identifies HbA1c >8% as representing preoperative glycemic imbalance requiring referral to a diabetologist before proceeding. 2
• Current glucose of 155 mg/dL (8.6 mmol/L) is within acceptable perioperative range and does not alter surgical candidacy. 1

Cardiac Testing is Not Indicated

• Routine preoperative cardiac troponin testing is not recommended for low-risk procedures like ankle surgery in asymptomatic patients. 1
• Preoperative risk assessment for ischemic heart disease should be performed only for patients at high risk or those with autonomic neuropathy or renal failure. 1
• This patient has normal vital signs, no mentioned cardiac symptoms, and is undergoing orthopedic (not cardiac or major vascular) surgery. 1
• Transthoracic echocardiogram would only be indicated if there were clinical signs of heart failure or significant cardiac autonomic neuropathy, which are not present. 1

Coagulation Studies are Not Required

• Hemoglobin, PT, and INR are not routinely indicated for patients on metformin monotherapy without bleeding disorders or anticoagulant use. 1
• The patient's complete blood count is already documented as normal. 1
• Metformin does not affect coagulation parameters. 1

Essential Perioperative Management Steps

Medication Adjustments

• Hold metformin on the day of surgery to reduce risk of lactic acidosis, though this risk is minimal with normal renal function. 1, 3
• The patient is not on SGLT2 inhibitors (which would require discontinuation 3-4 days preoperatively), sulfonylureas, or insulin requiring dose adjustment. 1, 3

Glucose Monitoring Protocol

• Target perioperative glucose range of 100-180 mg/dL (5.6-10.0 mmol/L). 1, 3
• Monitor blood glucose every 2-4 hours while NPO and during the perioperative period. 1, 3
• Measure glucose within 4 hours of surgery. 1

Avoiding Common Pitfalls

• Do not delay surgery based on a single glucose reading of 155 mg/dL—the HbA1c of 6.8% reflects adequate chronic glycemic control. 1, 2
• Do not order "routine" preoperative cardiac testing for low-risk orthopedic procedures in asymptomatic patients with well-controlled diabetes. 1
• Ensure glucose monitoring uses whole blood (arterial or venous) rather than capillary measurements when possible for greater accuracy. 1
• If insulin becomes necessary perioperatively, use basal-bolus regimens rather than correction-only sliding scale insulin, as this significantly reduces complications. 1, 3

Special Considerations for This Patient

• The patient's dietary and lifestyle modifications with metformin have achieved good control (HbA1c 6.8%), indicating low perioperative risk. 1
• Normal comprehensive metabolic panel confirms adequate renal function, eliminating concerns about metformin-associated lactic acidosis or diabetic nephropathy complications. 1
• The ankle pathology (swelling, deformity, tenderness) does not suggest systemic complications requiring additional workup. 1