Review Question - QID 108760

A 64-year-old man presents to his physician 6 months after experiencing a myocardial infarction for a follow-up appointment. He denies any symptoms over the last several months. His past medical history is significant for type 2 diabetes, obesity, hypertension, and cyclothymia. His current medications include hydrochlorothiazide, metoprolol, metformin, insulin, fluoxetine, and fish oil. His temperature is 98.6°F (37°C), blood pressure is 131/82 mmHg, pulse is 91/min, and respirations are 14/min. The patient is a calm elderly man who is moderately obese and in no current distress. His cardiovascular exam is notable for an S4 heart sound. Laboratory results are shown below:

Serum:
Na+: 140 mEq/L
Cl-: 100 mEq/L
K+: 4.4 mEq/L
HCO3-: 23 mEq/L
BUN: 20 mg/dL
Glucose: 120 mg/dL
Creatinine: 1.6 mg/dL
Ca2+: 10.1 mg/dL
AST: 11 U/L
ALT: 9 U/L
Cholesterol: 190 mg/dL
Triglycerides: 150 mg/dL
High-density lipoprotein (HDL): 11 mg/dL
Low-density lipoprotein (LDL): 149 mg/dL

The physician changes the patient's medications during this visit. The patient returns 2 weeks later with a mean blood glucose of 167 mg/dL. He is also complaining of flushing that occurs occasionally but otherwise is doing well. Which of the following is most likely to alleviate this patient's current symptoms after the medication change?