Insulinoma Mimic: Tramadol-induced Hypoglycemia

Abstract

Endogenous hyperinsulinemia hypoglycemia has numerous etiologies. The objective of this report is to describe a patient with severe hyperinsulinemic hypoglycemia with no known history of diabetes or hypoglycemia who presented with acute altered mental status. Blood glucose was noted to be 40 mg/dL (2.22 mmol/L) (reference range 65-125 mg/dL; 3.61-6.94 mmol/L). The patient's sulfonylurea screen was negative. Following 1 mg glucagon injection, the patient's glucose did not improve, a response inconsistent with insulinoma. Imaging studies of the pancreas did not show pancreatic mass. Two weeks before the presentation, the patient started on tramadol for back pain with the dose increased 3 days prior to presentation. The patient's hypoglycemia resolved and returned to baseline 4 days after the initial presentation. Tramadol has been reported to cause hypoglycemia, especially in the elderly population. Tramadol may act on μ receptors on β cells to upregulate insulin secretion. When approaching a patient with endogenous hyperinsulinemia, one should consider tramadol or other analgesics as a possible etiology.

Keywords: endogenous hyperinsulinemia; hypoglycemia; tramadol.

Figure 1.

Computed tomography scan of abdomen with/without IV contrast shows fatty infiltration of the pancreas with moderate pancreatic atrophy although no evidence of hyper-enhancing focal masses to suggest insulinoma.