Insulinoma After Bariatric Surgery: Diagnostic Dilemma and Therapeutic Approaches

Abstract

Hypoglycemia is increasingly recognized as a complication of bariatric surgery. Typically hypoglycemia does not appear immediately postoperatively, but rather more than 1 year later, and usually occurs 1–3 hours after meals. While rare, insulinoma has been reported after bariatric surgery. Clinical factors which should raise suspicion for insulinoma and the need for comprehensive clinical and biochemical evaluation include hypoglycemia occurring in the fasting state, predating bariatric surgery and/or worsening immediately postoperatively, and lack of response to conservative therapy. Localization and successful resection of insulinoma can be achieved using novel endoscopic ultrasound and surgical approaches. In summary, hypoglycemia presenting shortly after gastric bypass or with a dominant fasting pattern should be fully evaluated to exclude insulinoma. Additionally, evaluation prior to gastric bypass should include screening for history of hypoglycemia symptoms.

Hypoglycemia After Gastric Bypass Surgery: Current Concepts and Controversies

“…A comprehensive history and physical exam also provide invaluable information to consider additional causes of hypoglycemia, such as malnutrition, side effects of medications or supplements, critical illness, hormone deficiencies, autoimmune hypoglycemia (3), or nonislet cell tumors (2). If hypoglycemia in well-appearing individuals occurs in the fasting state, then an additional workup should be performed to rule out insulinoma (4).…”

Heterogeneity of proliferative markers in pancreatic β-cells of patients with severe hypoglycemia following Roux-en-Y gastric bypass

“…Pathologic examination of pancreatic tissue from severely affected patients who underwent pancreatectomy reveals large and small islets, often of irregular shape and clustered near ducts, with nuclear atypia, similar to findings seen with nesidioblastosis unrelated to gastric surgery [4, 5, 22]. Insulinoma has also been reported rarely in post-bypass patients [23]; whether this is linked to stimulation of proliferation and clonal expansion or to increased diagnostic attention in post-RYGB patients remains uncertain. β-cell mass is quantitatively increased in some [24] but not all series [25], potentially due to small cohort sizes or heterogeneity among case or control samples.…”

Medical nutrition therapy for post-bariatric hypoglycemia: practical insights

“…PBH typically presents with postprandial hypoglycemia, occurring within 1 to 3 hours after eating. Hypoglycemia which also occurs in the fasting state should raise suspicion for autonomous secretion of insulin by an insulinoma or other hormonal or metabolic disorders [15]. Next, biochemical evaluation should be performed to determine whether hypoglycemia is associated with inappropriately increased insulin levels.…”