Diabetes Case 1

Patient Background:

A 64 year-old Caucasian woman with an 11-year history of type 2 diabetes is referred to you for further management. She is currently taking metformin 1000 mg bid, rosuvastatin 10 mg daily, and irbesartan 150 mg daily. Menopause was at age 47, and she has never taken any estrogen replacement therapy. Her examination is significant for a body mass index (BMI) of 32 kg/m2 (normal, 18.5 to 24.9 kg/m2), a blood pressure (BP) of 142/86 mm Hg, and decreased vibratory sensation in her feet with absent Achilles reflexes and pedal pulses. The patient does not have lower extremity edema.

Laboratory Results:

Glycated hemoglobin (A1c): 8.2% (normal, <5.7%)

Serum creatinine: 1.8 mg/dl (normal, 0.5 to 1.1 mg/dL)

Estimated glomerular filtration rate (eGFR): 28 mL/min/1.73 m2 (normal, >90 mL/min/1.73 m2)

Urine microalbumin/creatinine ratio of 62 mg/g (normal, <30 mg/g)

Low density lipoprotein (LDL) cholesterol: 93 mg/dL (normal, <100 mg/dL)

Question 1

Because the eGFR is <30/mL/min/1.73 m2, metformin was discontinued.
Which medication should be avoided given the patient’s eGFR?

Insulin Glargine
Correct Answer

The risk of hypoglycemia is greatly increased with use of glimepiride and glyburide with an eGFR <60 mL/min/1.73 m2 due to the presence of two active metabolites cleared in part by the kidney. Thus, use of glyburide should be avoided with an eGFR <60 mL/min/1.73 m2.

Insulin doses often need to be adjusted as renal function declines, but insulin can still be used in patients with chronic kidney disease (CKD). No dose adjustment is indicated with thiazolidinediones such as pioglitazone in patients with CKD. However, thiazolidinediones are associated with fluid retention, and they should be used with caution if edema is present. Only a small amount of linagliptin is cleared renally; thus, no dose adjustment is indicated in patients with a reduced eGFR.