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Perioperative management of diabetes: Translating evidence into practice

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For longer, more complex procedures, a switch to an IV insulin drip is safe and allows rapid adjustments in dosing and plasma glucose levels. Ideally, IV insulin is started prior to the procedure so that the glucose level is stable once the patient arrives in the operating room. Given the logistics of IV insulin management, including the need for frequent monitoring (hourly) and dose adjustments, this type of treatment should be reserved for environments with adequate numbers of trained staff.

IV regular insulin is therapy of choice

Adapted, with permission, from Diabetes Care (Goldberg PA, et al. Diabetes Care 2004; 27:461–467), Copyright © 2004 by the American Diabetes Association.

Figure 1. Yale insulin infusion protocol (for use in hyperglycemic adults in intensive care settings, but not specifically for diabetic emergencies).

Regular insulin delivered IV has a serum half-life of 7 minutes with a duration of effect of approximately 1 hour. These properties make IV regular insulin an effective tool for adjusting insulin therapy and addressing rapid changes in blood glucose values in critically ill patients. For this reason, IV regular insulin has become the preferred insulin for perioperative and critical care management. Although rapid-acting analogs can also be used IV, they confer no benefit over IV regular insulin and are more expensive.

Several different algorithms for IV regular insulin therapy are in use. Some are static, such as those of Markovitz et al 14 and Stockton et al, 15 while others are dynamic (ie, doses are self-adjusted based on changes in blood glucose level), such as the “Yale protocol” of Goldberg et al ( Figure 1 ).16

POSTOPERATIVE GLYCEMIC MANAGEMENT

Start subcutaneous transition before stopping IV drip

Transitioning from IV to subcutaneous insulin is often complicated. Nonoral nutrition options (ie, parenteral nutrition or enteral supplementation) must be considered. As noted, insulin must be replaced according to physiologic needs, which requires that a long-acting basal insulin be used regardless of oral intake status, a rapid-acting insulin be given to cover prandial or nutritional needs, and supplemental rapid-acting insulin be used to correct hyperglycemia.

In the transition from IV insulin, basal insulin replacement can begin at any time. I recommend starting the transition from IV to subcutaneous insulin about 12 to 24 hours before discontinuing the insulin drip. In type 1 diabetes, this transition ensures basal insulin coverage and minimizes the risk of developing ketones and ketoacidosis. In type 2 diabetes, it can ensure a more stable transition and better glycemic control.

Determining the basal insulin dose

Figure 2. The Miami 4/12 rule determines insulin dosing by dividing the patient’s weight in kilograms by 4 to calculate initial basal insulin replacement (in units per day) and by 12 to calculate prandial coverage (in units before each meal).

The starting dose of basal insulin should be 50% to 80% of the prior IV insulin total daily dose, if stable glycemic control had been achieved with IV insulin. Alternatively, a calculation called the “Miami 4/12 rule” can be used, whereby the basal insulin replacement dose is equal to the patient’s weight in kilograms divided by 4 ( Figure 2

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