In this study breath samples will be collected using three different methods to maximise the chemical information available from each breath. Breath samples from Type 2 diabetic patients will be compared with healthy controls. Subgroups will have repeated breath samples after drinking orange juice or during normal day-to-day activities. This is to measure any changes in breath chemicals over time. The chemicals detected will be compared with blood tests, to identify potential breath biomarkers for blood glucose concentration, and to see if factors such as sex, age, and diet have any effect on the biomarkers detected.