Orthostatic Hypotension: Given the patient's age, diabetes, and medication regimen (especially the use of bupropion, Effexor, and trazodone, which can affect blood pressure), orthostatic hypotension is a common and likely cause of dizziness, especially if it occurs when changing positions.

Hypoglycemia: Although the patient's A1c is well-controlled at 6.7, the use of metformin and glipizide can still lead to episodes of hypoglycemia, which can cause dizziness.
Dehydration: Elderly patients, especially those with diabetes, are at risk for dehydration, which can lead to dizziness.
Medication Side Effects: Besides orthostatic hypotension, other medications like bupropion, Effexor, and trazodone can have side effects that include dizziness.

Cardiac Arrhythmias: Conditions such as atrial fibrillation or other arrhythmias can cause dizziness and are potentially life-threatening if not addressed.
Stroke or Transient Ischemic Attack (TIA): Although less likely given the description of a single episode of dizziness without other neurological deficits, stroke or TIA must be considered due to their severe consequences.
Severe Anemia: Could lead to dizziness due to reduced oxygen delivery to tissues.

Vestibular Disorders: Conditions affecting the inner ear, such as benign paroxysmal positional vertigo (BPPV), Meniere's disease, or vestibular neuritis, can cause dizziness but are less likely given the patient's presentation.
Endocrine Imbalances: Other than diabetes, imbalances such as thyroid disorders can cause dizziness but would be less common without other symptoms.
Autonomic Dysfunction: Can occur in diabetes but is less common and would typically present with other autonomic symptoms.