[Reactive hypoglycaemia, a mysterious, insidious but non dangerous critical phenomenon]

Numerous individuals complain of malaise attributed to hypoglycaemia. However, the diagnosis of hypoglycaemia is rarely documented and most often overstated. Reactive hypoglycaemia in the postprandial state is rather exceptional. The diagnosis relies upon the measurement of plasma glucose concentration (< 3 mmol/l or 55 mg/dl) at the time of the malaise. Reactive hypoglycaemia is generally associated with adrenergic symptoms and, less often, with cognitive disturbances. Importantly, a plasma glucose concentration below 3 mmol/l during an oral glucose tolerance test is not sufficient to decide that the patient suffers from reactive hypoglycaemia. Treatment is based on dietary advices including frequent small split meals and limitation of carbohydrates with high glycaemic index. Acarbose, a specific inhibitor of gut alpha-glucosidase enzymes, may be helpful in case of diet failure. As compared with true reactive hypoglycaemia, a postprandial hyperadrenergic reaction without real concomitant hypoglycaemia is much more prevalent. Careful anamnesis may suspect such a diagnosis, but other diagnoses such as panic attack or vasovagal reaction should be excluded. Treatment is purely symptomatic and essentially empiric.