Following ethical consent participants will be asked to complete one food frequency questionnaire (FFQ) and one quality of life (QOL) questionnaire. A subgroup of these participants (approximately 10 CSII users and 10 MDI users) will then be asked to take part in one interview to investigate quality of life and complete a food diary to explore eating behaviours. All participants consenting to the cross-sectional arm of the study will also be asked to provide an extra volume of blood for analysis. This will be taken at the same time and in addition to their regular diagnostic sample, however where this is unfeasible extra occasional appointments may be needed. (Please be aware that the interview, food diary and blood sample are all optional and that the minimum requirement for participation in the study is the completion of the FFQ and the QOL questionnaires). Results will be compared with existing patient medical records, which will also be analysed during the study.