Board Review: Internal Medicine
You’re working in the ICU overnight and a patient is admitted from the ED for sepsis. Patient has a past medical history of DM, HTN, COPD. On arrival to the ICU patient is altered and unable to provide further history. Per family, he has not been compliant with medications over the past two months secondary to difficulties with insurance. Blood sugar on arrival is 450. Repeat blood sugar one hour later is 495. After obtaining a medication reconciliation you find out that the patient takes metformin, glipizide, and sitagliptin. As you are entering medications for the patient you debate the appropriate medication regimen to control his blood sugar. What is the most appropriate medication to start at this time?
Restart all home medications: metformin, glipizide, sitagliptin
Start insulin infusion until blood glucose is under 200
Begin sliding scale insulin every 6 hours
Start insulin NPH BID and humalog before meals
Answer- B- start insulin infusion until blood glucose is under 200.
Hyperglycemia has been found to be detrimental to critical care patients. Patients with uncontrolled hyperglycemia are at increased risk for further metabolic abnormalities including DKA and HHNK. Septic patients requiring ICU level care are typically started on IV steroids, which only exacerbates the issue. Starting an insulin infusion allows for rapid correction of glucose. After glucose control is achieved these patients can be transitioned to both basal and prandial insulin. Total daily dose of insulin is estimated to be .2-.4 units/kg/day. Typically half of this (.1 units/kg/day) is given in the form of basal insulin while the remainder is given is 3-4 pre-prandial doses. Another method to calculate the appropriate dose in patients that are very resistant to insulin is to summarize the total amount of insulin infusion given over a 24 hour period. Give half that amount in the form of basal insulin and divide the rest into prandial doses. Sliding scale insulin every 6 hours should be used in altered patients who are not able to tolerate PO safely. Oral diabetic medications should be held in the critical setting.
Stable patients presenting to the ED without a known diagnosis of DM but are found to meet any of the following criteria can be initiated on diabetic therapy:
Fasting glucose >126
2 hour glucose tolerance test >200
Random glucose >200
Hemoglobin A1c >6.5%
Routine labs including CBC and BMP should be collected prior to initiating therapy. If creatinine is less than 1.4, patients can be started on metformin 500mg/day prior to discharge. These patients need close follow up with PCP. Patients that are very symptomatic (i.e. polydipsia, fatigue, weight loss) likely require observation versus admission for initiation of subcutaneous insulin and patient education.
Goyal, N. & Schlichting, A.B.. (2016). Section 17: Endocrine Disorders. In Tintinalli's Emergency Medicine: A Comprehensive Study Guide (8th ed., pp. 1441-1456). New York, NY: McGraw-Hill Education.
Jacobi, Judith, PharmD, FCCM, Bircher, Nicholas, et al. Guidelines for the use of an insulin infusion for the management of hyperglycemia in critically ill patients. Crit Care Med. 2012;40(12):3251-3276. doi:10.1097/CCM.0b013e3182653269