A 48-year-old man with type 2 diabetes mellitus comes to the office for a follow-up appointment. The patient was diagnosed 4 years ago and was initially managed with metformin, but that medication had to be discontinued due to diarrhea. He is currently being treated with the maximum therapeutic dose of glipizide, but has persistently elevated blood glucose levels. Laboratory results show a fasting blood glucose of 180 mg/dL and hemoglobin A1c of 8.6%. The patient does not want to take insulin or other injectable diabetic medications. After discussing various treatment options, canagliflozin is added to his current regimen. Which of the following tests should be ordered prior to initiating the new therapy in this patient?

Question

A 48-year-old man with type 2 diabetes mellitus comes to the office for a follow-up appointment.  The patient was diagnosed 4 years ago and was initially managed with metformin, but that medication had to be discontinued due to diarrhea.  He is currently being treated with the maximum therapeutic dose of glipizide, but has persistently elevated blood glucose levels.  Laboratory results show a fasting blood glucose of 180 mg/dL and hemoglobin A1c of 8.6%.  The patient does not want to take insulin or other injectable diabetic medications.  After discussing various treatment options, canagliflozin is added to his current regimen.  Which of the following tests should be ordered prior to initiating the new therapy in this patient?

Quizplus · Accepted Answer

11ec160b_3bad_cda4_9249_df5e0a30c4c5_MD0001_00 Sodium-glucose cotransporter 2 (SGLT2) is a low-affinity, high-capacity transport protein that is responsible for reabsorbing 90% of filtered glucose in the proximal tubule. SGLT2 inhibitors (eg, canagliflozin, dapagliflozin) are oral antidiabetic agents that decrease renal reabsorption of glucose, leading to increased urinary glucose loss and decreased blood glucose levels. They are primarily used in patients who do not tolerate or have inadequate diabetic control with first-line medications (eg, metformin). The effectiveness of SGLT2 inhibitors is dependent on glomerular filtration of glucose, which is decreased in patients with chronic kidney disease. For this reason, an estimate of glomerular filtration with serum creatinine is recommended prior to initiation of therapy and periodically thereafter. Side effects include genitourinary tract infections due to glucosuria and moderate osmotic diuresis that can cause symptomatic hypotension (particularly in elderly individuals and patients taking diuretics). (Choice A) A leukocyte count is not required before initiating treatment with antidiabetic agents. (Choice C) Certain drugs such as diuretics (eg, thiazide, loop) and antituberculosis drugs (eg, pyrazinamide, ethambutol) reduce uric acid clearance and may precipitate gout. However, SGLT2 inhibitors are associated with increased uric acid excretion. (Choice D) Thyroid function tests are routinely performed on patients taking lithium and amiodarone as these drugs can alter thryoid hormone metabolism. However, thyroid function tests are not required for antidiabetic medications. (Choice E) Although SGLT2 inhibitors increase the risk of urinary tract infections, urinalysis prior to initiating therapy would not be of use. Educational objective: Sodium-glucose cotransporter 2 inhibitors (eg, canagliflozin, dapagliflozin) decrease renal reabsorption of glucose, leading to urinary glucose loss and decreased blood glucose levels. In patients with chronic kidney disease, these medications are less effective. Therefore, serum creatinine should be measured prior to therapy. __________ References: A novel therapeutic agent for type 2 diabetes mellitus: SGLT2 inhibitor. (http://www.ncbi.nlm.nih.gov/pubmed/25215272)

A 48-Year-Old Man with Type 2 Diabetes Mellitus Comes to the Office