A 52-year-old man with a 10-year history of type 2 diabetes mellitus presents with a 6-week history of depressed mood, fatigue, insomnia, and loss of appetite. He reports feeling 'empty inside' with no interest in his hobbies. His wife notes he has become increasingly irritable and withdrawn. He denies suicidal thoughts but expresses hopelessness about his future. Current medications include metformin and lisinopril. Physical examination is unremarkable. HbA1c is 8.2%, and thyroid function tests are normal. Which of the following is the MOST important consideration in selecting an antidepressant for this patient?