INS and diabetes mellitus: However, these guidelines do not provide clear criteria or classification pathways for clinical use.8,9 A pragmatic classification algorithm (Figure 1) was thus developed in 2010 by key diabetes stakeholders in the UK, and published by the Royal College of General Practitioners (RCGP) and (the previously existing) NHS Diabetes in their Coding, Classification and Diagnosis of Diabetes document.4 This uses age at diagnosis and time to commencing insulin treatment from diagnosis as its diagnostic criteria.