MKSAP Quiz: type 1 diabetic admitted for hip replacement
This month's quiz asks readers to evaluate a 62-year-old man with a 36-year history of type 1 diabetes mellitus admitted to the hospital for a right hip replacement.
A 62-year-old man is admitted to the hospital for a right hip replacement. The patient has a 36-year history of type 1 diabetes mellitus. He also has proliferative diabetic retinopathy treated previously with laser therapy and peripheral and autonomic neuropathy. Before admission, the patient's diabetes was treated with premixed 70/30 insulin (neutral protamine Hagedorn [NPH] insulin/regular insulin); he took 18 units of this preparation before breakfast and 12 units before his evening meal. His most recent hemoglobin A1c value indicated good glycemic control.
On physical examination, temperature is normal, blood pressure is 138/79 mm Hg, pulse rate is 88/min, and respiration rate is 16/min; BMI is 22. Other physical examination findings are consistent with the previously established diagnoses of diabetic retinopathy with laser scars, autonomic neuropathy, and osteoarthritis of the right hip.
Which of the following is the most appropriate insulin therapy after surgery?
A. Insulin glargine once daily and insulin aspart before each meal
B. Intravenous insulin infusion
C. Previous schedule of 70/30 insulin
D. Sliding-scale insulin schedule with regular insulin given whenever the blood glucose
level is 150 mg/dL (8.3 mmol/L) or greater
E. Subcutaneous insulin infusion
MKSAP Answer and Critique
The correct answer is A. Insulin glargine once daily and insulin aspart before each meal. This item is available to MKSAP 16 subscribers as item 63 in the Endocrinology section. Information about MKSAP 16 is available online.
This patient should begin receiving insulin glargine (once daily) and insulin aspart (before each meal) after surgery. A patient with long-standing type 1 diabetes mellitus makes no endogenous insulin and needs a flexible insulin regimen that includes half his daily requirements as a basal insulin (such as insulin glargine) and the rest as boluses of rapid-acting insulin (such as insulin aspart) before meals.
Neither intravenous nor subcutaneous insulin infusions are necessary in this patient, and both would likely require his transfer to the intensive care unit for safe administration.
Given his unpredictable levels of activity and eating while in the hospital, restoring the patient's previous outpatient dosage of premixed insulin is inappropriate.
A sliding scale that does not include basal insulin and does not begin insulin administration unless the blood glucose level is at or above 150 mg/dL (8.3 mmol/L) will cause wide swings from hyperglycemia to hypoglycemia and thus is inappropriate treatment for this patient.
Key Point
- A sliding-scale insulin regimen that includes no basal insulin is inappropriate for a hospitalized patient with diabetes mellitus.