A 51-year-old Caucasian female with diabetes mellitus type 2 comes to the office for a routine follow-up visit. She has no other medical problems. Her medications include glyburide, metformin and pioglitazone. Examination shows no abnormalities. The patient’s laboratory tests reveal the following:
Serum Na Serum K Chloride Bicarbonate BUN Serum creatinine Calcium Blood Glucose
136 mEq/L 4.2 mEq/L 98 mEq/L 20 mEq/L 48 mg/dl 2.4 mg/dl 9.8 mg/dl 172 mg/dl
What is the most effective strategy to manage this patient’s uncontrolled diabetes?
- A. Stop glyburide and add insulin. [1 0%]
- B. Stop metformin and add insulin. [29%]
- C. Stop glyburide and pioglitazone; add insulin. [24%]
- D. Stop pioglitazone and metformin; add insulin. [1 4%] .,
- E. Stop glyburide and metformin; add insulin. [22%]
Explanation: User ld:
The patient has an anion gap metabolic acidosis, and is developing renal failure. The above laboratory data is insufficient to determine if the metabolic acidosis is related purely to renal failure secondary to diabetes, or is associated with the use of metformin. Metformin use must therefore be stopped. Glyburide use must be stopped, as well, since the drug is metabolized extensively by the kidneys. Renal failure will increase the half-life of glyburide, leading to pronounced adverse effects, such as hypoglycemia.
The United Kingdom Prospective Diabetic Study (UKPDS) study demonstrated the value of the combined use of oral hypoglycemics and insulin therapy for diabetes control. Insulin is the mainstay of therapy for diabetic patients with renal failure. Since pioglitazone is metabolized by the liver, there is no need for it to be withdrawn.
Educational Objective: Renal failure is an indication to manage a diabetic patient with insulin. It is recommended to stop metformin and other sulfonylureas that are metabolized exclusively by the kidneys, in order to avoid toxicity and adverse events. Rosiglitazone, pioglitazone, acarbose or repaglinide are alternatives to continue oral therapy.