A low blood sugar level (hypoglycaemia) is a common problem in new-born babies, and sometimes causes brain damage. However, it is not known which babies will suffer brain damage or at what blood sugar levels. The duration, severity and frequency of the hypoglycaemia may all be important. In order to learn more about which of these aspects of hypoglycaemia are important for brain damage, we wish to study a group of two-year-olds who had continuous monitoring of their sugar levels in the first few days after birth. We will assess their mental and physical development, memory, vision and general health, and relate these outcomes to the periods of hypoglycaemia that many of them experienced as new-borns. This information will help provide critical information about how new-born babies should be monitored and treated in order to prevent brain damage with its long-term consequences while minimising unnecessary interventions in new-born babies.