The passive (tilting) orthoclinostatic test was performed on 44 young subjects affected by type 1 insulin-dependent diabetes. In 11 cases the test was repeated after a 3-4 years interval. The results, compared with age matched controls, showed in the diabetic patients a supersensitivity of the two antagonist systems, increasing with age and duration of the disease, up to an overexcitability and a functional exhaustion. It would thus seem that diabetic dysautonomia involves not only the peripheral nervous system but also the hypothalamic centers, with an impoverishment of the capacity of self-regulation. The hypersympathicotonus in diabetic young patients seems to be only apparent, as a result of the hypersensitivity of an overstimulated system.