Decreasing Hemoglobin A1c: Progress or Pathology?

A 67-year-old woman with multiple comorbidities presented to the clinic for a routine follow-up of her chronic conditions, including diabetes management. She had been followed by multiple residents over the years and was noted to have a declining hemoglobin A1c (HgbA1c) despite discontinuation of diabetes medications and no significant lifestyle changes. The patient reported episodes of hypoglycemia, dizziness, and multiple falls, resulting in several emergency department visits. Her HgbA1c had decreased from a prior high of 10% to 5.4%. Further evaluation included laboratory tests, imaging, and an e-consult to Endocrinology. Diagnostic evaluation revealed elevated insulin (47.8 μU/mL; reference range: 2-25 μU/mL) and c-peptide (11.2 ng/mL; reference range: 0.5-2 ng/mL) in the presence of hypoglycemia (serum glucose 42 mg/dL). Computed tomography (CT) and magnetic resonance imaging (MRI) identified a mass in the pancreatic tail. Endocrinology recommended urgent surgical consultation, and one month later, the patient underwent distal pancreatectomy and splenectomy. Final pathology confirmed an insulinoma. She was subsequently followed by her primary care physician, surgical team, and Endocrinology, resumed metformin, and has had no further hypoglycemic episodes or falls. Insulinoma is a rare diagnosis that, if overlooked, can lead to significant morbidity. While treatment is typically straightforward once identified, diagnosis often requires careful attention to subtle clinical clues. This case illustrates how a patient with multiple chronic conditions and an improving HgbA1c could easily be overlooked in a busy resident-run clinic. It also demonstrates the importance of careful evaluation before attributing improvements in HgbA1c solely to treatment adjustments, as well as the value of multidisciplinary coordination in diagnosing and treating underlying disease in a timely manner.