The study design is a repeated measures study involving the provision of a standard high protein/high fat evening test meal on 3 different evenings within a 7-day period in the same study subject. The children/adolescents will be instructed to give an insulin dose for the carbohydrate before the meal (calculated using their optimal insulin to carbohydrate (ICR) - 20%). In addition they will have an additional dose for the fat and protein content either before (together with the dose for the carbohydrate in the meal [control meal]), 1 hour after, or 2 hours after the meal. These will be carried out in a random order in each subject. Continuous glucose monitoring (CGM) will be carried out for the whole 7 day period. Questionnaires will assess the acceptability to young people and their parents of the extra insulin doses.