A 49-year-old woman with type 2 diabetes presents with profuse watery diarrhea persisting despite 24-hour fasting, muscle weakness, and facial flushing. Vital signs show BP 118/76 mmHg, HR 102/min, RR 16/min, temp 37.2°C. Laboratory studies reveal serum potassium 2.8 mEq/L, gastric pH 6.2 with markedly reduced acid secretion, and fasting glucose 156 mg/dL. Abdominal imaging shows no obstruction. She takes metformin and lisinopril. Which diagnosis best explains her presentation?

1. A)Carcinoid tumor
2. B)Glucagonoma
3. C)Insulinoma
4. D)Gastrinoma
5. E)VIPomaGABARITO