Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 67-year-old woman is transferred to the cardiothoracic intensive care unit (ICU) after undergoing repair of an abdominal aortic aneurysm. She has a 12-year history of type 2 diabetes mellitus.

Her blood glucose level on arrival at the ICU is 289 mg/dL (16.0 mmol/L). Although no longer on a cardiopulmonary bypass pump, she remains intubated and on vasopressors.

Which of the following is the best treatment to control her blood glucose level during her ICU stay?

A. Insulin glargine, once daily
B. Intravenous insulin infusion
C. Neutral protamine Hagedorn (NPH) insulin, twice daily
D. Regular insulin administered on a sliding scale

MKSAP Answer and Critique

The correct answer is B. Intravenous insulin infusion. This item is available to MKSAP 15 subscribers as item 40 in the Endocrinology section. Part A of MKSAP 16 was released on July 31. More information is available online.

The intensive control of glucose levels in hospitalized patients during critical illness has garnered substantial attention over the past decade. Several randomized clinical trials have shown a benefit to patient morbidity and mortality with stringent glycemic control. Whereas the precise target remains controversial, the bulk of the data suggests that treating to achieve glucose levels between 140 and 180 mg/dL (7.8 and 10.0 mmol/L) may be optimal. In the setting of an ICU, this is best and most safely achieved through the use of intravenous insulin. Intravenous delivery of insulin allows for more rapid titration and does not rely on subcutaneus absorption, which may be diminished or delayed in patients with cardiogenic shock or other critical illnesses associated with poor peripheral circulation.

If it appears that ongoing insulin is required once this patient is ready for transfer to a general ward, she should be transitioned to an injectable regimen involving long- or intermediate-acting and rapid-acting insulins. Oral agents can be restarted before discharge as long as renal function is normal and no contraindications exist.

Insulin glargine, the dosage of which is typically adjusted every 2 to 3 days until optimal glycemic control is achieved, cannot quickly guarantee adequate control during the 1 to 2 days that this patient is likely to be in the ICU. For similar reasons, using neutral protamine Hagedorn (NPH) insulin twice daily is unlikely to be the best treatment.

Although the dosage of regular insulin can be adjusted more frequently when administered on a sliding scale, this approach to glycemic control is considered inadequate because insulin is provided only when hyperglycemia becomes established. This method is not proactive enough to result in acceptable glycemic control during an ICU stay.

Key Point

• Intensive glycemic control is best achieved in the intensive care unit with an intravenous insulin infusion.

Learn more about ACP’s MKSAP 16.

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