Commentary by Mary Vouyiouklis MD, Fellow, and Ann Danoff MD, Director, Division of Endocrinology, Diabetes and Metabolism, NYU Medical Center
Welcome to our special diabetes series intended to highlight the essentials of diabetes care in the inpatient setting. For the next several weeks, we plan to present individual cases followed by some management questions and answers.
Case 1: The case of Mr. Smith
Mr. Smith is a 65 year old obese male admitted to the hospital with acute renal failure. He reports a recent history of diarrhea (up to 6 episodes of loose non-bloody stools per day for one week). He cannot keep anything down. His laboratory data reveals a BUN of 45 and a creatinine of 3 (baseline creatinine is 1). His admission non-fasting glucose is 168. He was diagnosed with Type 2 Diabetes 5 years ago, and his outpatient medications include glyburide 5 mg and metformin 1g bid. How would you manage his diabetes in the hospital?
A. Continue with both glyburide and metformin.
B. Discontinue glyburide. Continue with metformin.
C. Discontinue both oral meds. Do nothing else.
D. Start rapid acting insulin sliding scale qAC and check FS qAC, qHS.
E. QID Regular Insulin Sliding Scale (RISS)
As the patient is in renal failure, it is prudent to discontinue his glyburide and mandatory to discontinue the metformin. Glyburide has a long half life and is cleared by the kidney; therefore, he has an increased risk of becoming hypoglycemic under these conditions. In addition, because the risk of lactic acidosis increases in patients on metformin in the face of deteriorating renal function, metformin should not be used in men or women whose creatinine level is > 1.5 and 1.4 respectively. Several approaches would be acceptable in the patient described here. One approach would be to calculate the TDD (total daily dose) of insulin he requires, starting at a low 0.3 units/kg/day (especially in view of his compromised renal function). Half of the TDD should be given as a basal dose, provided either as a single injection of glargine or as NPH administered before breakfast and at 10 PM in equally divided doses. The remaining half the TDD of insulin should be given as a bolus of rapid acting insulin divided equally and administered ~15 minutes before each meal. Alternatively, the patient could be started on a rapid acting insulin sliding scale qAC. If the second approach is selected, after 48 hours, when total daily dose of insulin has been determined, his regimen should be adjusted to a qHS basal and pre-meal “bolus” regimen.
A regular insulin sliding scale insulin regimens (“RISS”) given “QID” (i.e., not given in relationship to meals), is strongly discouraged in patients who are eating. RISS treats rather then prevents hyperglycemia. Further, RISS is associated with the risk of insulin “stacking”. This may result in “roller coaster” glycemic control, i.e., hypoglycemia followed by rebound hyperglycemia. Whichever regimen is selected, fingerstick monitoring should be performed before each meal and qHS, and the regimen adjusted to achieve a fasting blood glucose of 80 – 120 mg/dl, and a 2 h post-prandial glucose of < 180 mg/dl. For patients admitted to the hospital who have excellent glycemic control on oral agents, these may be used as long as there are no contraindications (remember to stop metformin for 48 hours following a study using contrast; remember to stop a TZD for patients admitted in CHF, etc.). If changing needs are anticipated (as is often the case in hospitalized patients), these can usually be addressed more successfully with insulin.