How should type 2 diabetes mellitus (DM) be managed in patients undergoing surgery?

Updated: Oct 23, 2019
  • Author: Romesh Khardori, MD, PhD, FACP; Chief Editor: George T Griffing, MD  more...
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Answer

Surgical patients may experience worsening of glycemia for reasons similar to those listed above for intercurrent medical illness. Patients on oral agents may need transient therapy with insulin to maintain blood glucose at approximately 100-180 mg/dL.

In patients who require insulin, scheduled doses of insulin (eg, glargine once daily plus glulisine before meals, as opposed to sliding-scale insulin, are far more effective in controlling glucose. Intensive glucose control in surgical ICU patients appears to reduce the risk of septicemia, but as with other critically ill patients, this may come at the cost of increased risk of hypoglycemia. [314]

A standardized protocol can be effective in transitioning patients who have diabetes and acute coronary syndrome to subcutaneous insulin once oral feeding has resumed. This is based on insulin requirement during the previous 12 hours. Half of the amount is given as basal insulin, and the remainder is given as prandial insulin. [320]

For patients who can eat soon after surgery, the time-honored approach of administering half of the usual morning dose of neutral protamine Hagedorn (NPH) insulin with 5% dextrose in the IV infusion is acceptable, with resumption of scheduled insulin (perhaps at reduced doses) within the first 1-2 days. With the availability of newer basal insulins (ie, glargine, detemir), options have expanded. A full dose of basal insulin can be given, and rapid-acting insulin can be administered when meals are consumed.

Patients receiving basal insulin can often receive their usual dose if they are given IV glucose during surgery, with appropriate intraoperative and postoperative monitoring of glucose. Oral antidiabetic agents can be restarted when the patient is stable and eating.

Insulin secretagogues should be used with caution in the hospital, since food intake may be interrupted by diagnostic tests and procedures. Metformin may have to be started at a lower dose and gradually titrated to full dose due to GI side effects. Since TZDs have such a long biologic effect, their omission in the hospital is usually inconsequential. The role of incretins in the hospital has not yet been defined.

For patients who require more prolonged periods without oral nutrition and for major surgery, such as coronary artery bypass grafting and major abdominal surgery, constant infusion IV insulin is preferred. Discontinue metformin temporarily after any major surgery until the patient is clearly hemodynamically stable and normal renal function is documented. Discontinuing metformin for at least 48 hours in this situation until proof of normal renal function is established is the current standard.


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