Obesity with insulin resistance in the paediatric population provides an increasing challenge. Children with neurological or neuromuscular diseases are even more prone to obesity: their locomotor impairment leads to an increasingly sedentary lifestyle, a decrease in physical fitness and an increase in body fat (1-3). Obesity, in turn, can be associated with a decrease in physical fitness and a further increase in body fat. In this study we want to evaluate the effect of an insulin-sensitizer, metformin, in a group of overweight/obese patients with neurological or neuromuscular diseases. Metformin is a well-established insulin sensitizer.