Preoperative Overnight Management for Diabetic Patients
On the evening before surgery, diabetic patients should take their usual insulin dose at the regular time, eat normally, and stop metformin from that evening onward, while all other oral hypoglycemic agents continue until the morning of surgery. 1
Evening Before Surgery: Medication Management
Insulin Therapy
- Administer all insulin at the usual dose the evening before surgery, including both basal insulin (NPH, glargine, degludec/Tresiba, or detemir) and any prandial insulin with the evening meal 1, 2
- Maintain insulin pumps at usual settings until arrival at the surgical unit the next morning 1
- Never allow insulin deficiency in insulin-treated patients, as this leads to ketoacidosis within hours, particularly critical in Type 1 diabetes 1, 2
Oral Hypoglycemic Agents
- Stop metformin from the evening before surgery to reduce lactic acidosis risk, particularly important given potential perioperative renal stress 1, 2, 3
- Continue all other oral agents (sulfonylureas, DPP-4 inhibitors, GLP-1 agonists) with the evening meal 1
- SGLT2 inhibitors should have been discontinued 3-4 days prior to surgery due to euglycemic ketoacidosis risk 3
Evening Before Surgery: Nutritional Management
- Patients should eat their normal evening meal without restriction 1
- No preoperative glucose infusion is necessary the night before surgery 1
- Fasting begins after the evening meal according to standard NPO guidelines 1
Critical Preoperative Assessment Elements
The evening consultation or preoperative visit should document:
Gastroparesis Screening
- Ask specifically about abdominal bloating, early satiety, postprandial fullness, nausea, or vomiting, as gastroparesis occurs in 30-50% of Type 2 diabetes patients and necessitates rapid sequence intubation planning 2
Cardiac Autonomic Neuropathy
- Evaluate for orthostatic symptoms, postprandial hypotension, or exercise intolerance, as cardiac autonomic neuropathy increases cardiovascular events and sudden death risk perioperatively 2
- This is particularly important as silent myocardial ischemia is present in 30-50% of Type 2 diabetes patients 1, 2
Renal Function
- Confirm creatinine and GFR measurement is available, as diabetic nephropathy aggravates perioperative acute renal failure risk 1, 2
Recent Glycemic Control
- Document capillary blood glucose patterns from the past week, as recent disequilibrium affects perioperative management even with known HbA1c 2
- Identify any hypoglycemic episodes requiring assistance, as hypoglycemia unawareness occurs in 10% of insulin-treated Type 2 diabetes patients 2
- Check for recent ketosis with urinary or blood ketones, as this mandates surgery postponement except for life-threatening emergencies 2
Common Pitfalls to Avoid
- Never withhold basal insulin the evening before surgery, even if the patient will be NPO—this creates dangerous insulin deficiency 1, 2
- Never continue metformin past the evening before surgery, as perioperative stress and potential renal compromise increase lactic acidosis risk 1, 2, 3
- Never use sliding scale insulin alone without basal insulin coverage, as this leads to erratic glucose control 2
- Never assume SGLT2 inhibitors were stopped appropriately—verify they were discontinued 3-4 days prior 3
Morning of Surgery Management
For completeness, the morning approach differs based on insulin type: