Whipple's triad is a collection of three criteria (called Whipple's criteria) that suggest a patient's symptoms result from hypoglycemia that may indicate insulinoma. The triad is stated in various versions, but the essential conditions are:
- Symptoms known or likely to be caused by hypoglycemia especially after fasting or heavy exercise
- A low plasma glucose measured at the time of the symptoms
- Relief of symptoms when the glucose level is raised
The criteria date back to the 1930s, when it had been discovered that a few patients with hypoglycemic symptoms (such as shakiness, syncope, or sweating) due to hypoglycemia could be cured by surgery to remove an insulinoma. However, it had also become apparent that a large proportion of people with symptoms suggestive of hypoglycemia had no need of surgery. Diagnostic testing was rudimentary: beyond a crude assay for reducing substances as an indirect measure of blood glucose, there was no way to measure hormones and metabolites such as insulin, and no imaging procedures for internal organs such as the pancreas.
Allen O. Whipple was a well-known surgeon who had pioneered pancreatic surgery. In an article entitled "The surgical therapy of hyperinsulinism", in J Internat Chir 3:237-276 (1938), he proposed that no pancreatic surgery to look for an insulinoma be performed unless these criteria were met.
The use and significance of the criteria have evolved over the last century as our understanding of the many forms of hypoglycemia has increased and diagnostic tests and imaging procedures have improved. Whipple's criteria are no longer used to justify surgical exploration for an insulinoma, but to separate "true hypoglycemia" (in which a low glucose can be demonstrated) from a variety of other conditions (e.g., idiopathic postprandial syndrome) in which symptoms suggestive of hypoglycemia occur but low glucose levels cannot be demonstrated. The criteria are now invoked far more often by endocrinologists than by surgeons. The radiological investigation of choice now is endoscopic and/or intraoperative ultrasonography.