Insulinoma in Type 2 Diabetes Mellitus Becoming Clinically Evident in the Setting of Acute Kidney Injury: A Case with a Postoperative Deterioration of the Glucose Metabolism and a Quantitative Islet Cell Analysis.

Insulinoma rarely coexists with type 2 diabetes mellitus and it may thus remain clinically unrecognized. We describe a case of a 73-year-old man with long-standing type 2 diabetes mellitus in whom recurrent hypoglycemia became evident during progressive renal dysfunction after acute kidney injury. Following an aneurysm repair and distal pancreatectomy, hypoglycemia resolved, but his glucose metabolism deteriorated markedly. A quantitative analysis of non-tumorous pancreatic tissue revealed an intermediate β-cell area and a relatively increased α-cell area. A postoperative glucose deterioration is likely multifactorial, reflecting distal pancreatectomy, long-standing diabetes with limited β-cell reserve, and chronic renal dysfunction. This case highlights the complexity of the glucose metabolism in patients with insulinoma.