[Functional hypoglycemia. Fancy or fact?]

Abstract

Idiopathic reactive or functional hypoglycemia is not a recognised disease entity. It is defined solely on the basis of a history of hypoglycemic symptoms in everyday life, which can be relieved by food intake. However, the general opinion is that functional hypoglycemia exists, but it is not a frequent condition. The coincidence of a low blood glucose nadir and hypoglycemic symptoms in the hypoglycemic phase of the oral glucose tolerance test is not diagnostic of functional hypoglycemia. Endocrine dysfunction has never been demonstrated. The logical approach to the problem is to study blood glucose values during everyday life and at the onset of symptoms. This has been done in two controlled studies using reliable monitoring techniques. Low blood glucose concentrations during attacks could only be demonstrated in one of the studies and only in some of the subjects. Furthermore, the pattern of recorded symptoms was independent of the measured levels. Thus, these patients are probably not hypoglycemic in the true sense of the word. In a recent controlled but unblinded study, a higher blood glucose threshold for the onset of hypoglycemic symptoms was demonstrated in a group of patients with functional hypoglycemia. This, combined with a highly refined diet poor in fibre and starch, could provide symptomatic oscillations of blood glucose levels. However, much more research is needed in this field, before any conclusions are drawn.