[Flat curves of oral glucose tolerance tests (author's transl)]

Patients are often referred to diabetologists on account of a flat curve of oral glucose tolerance test. This abnormality, however, is virtually never associated with a serious metabolic disorder and in any case, it never points to a disease that cannot be diagnosed by questioning or by straightforward clinical examination, nor confirmed by a more specific laboratory test. The curve may be flat for technical reasons (e.g. rejection of the glucose administered, timing of blood withdrawals and assays), for physiological reasons (differences between venous and arteriolo-capillary blood), or for pathological reasons (interaction with drugs, pituitary, thyroid or adrenal insufficiency, digestive malabsorption) but it never implies organic hypoglycaemia nor diabetes mellitus.