how can we defferentiate between hypoglycemia caused by factitious insulin injection and by an insulinoma?

Question

lets put it in another way on measuring blood insulin level how can we know whether its endogenous or exogenous

Answer 1

Just to help others here, may I rephrase?.... How can we tell the difference between low blood sugar resulting from man made insulin verses insulin from insulinoma (insulin produced from a beta cell tumor on the pancreas).

One would need to carefully monitor food intake and insulin injections while monitoring blood glucose with a CGMS (continuous glucose monitoring system). Insulinoma produces hypoglycemic epsiodes at improbable times whereas regular injections of insulin (man made or other) would produce more predictable hypoglycemia.

Answer 2

I think the easiest way would be just to restrict the exogenous injection of insulin, and then subsequently monitor blood glucose. If caused by insulinoma, there should really be no change in observed hypoglycemia, while the other situation will result in higher glucose levels.