INS and type 1 diabetes mellitus: In a UK cohort, approximately 25% of those aged >30 years who were initially diagnosed and treated as having type 2 diabetes but progressed to insulin treatment within 3 years developed near absolute insulin deficiency (non-fasting C-peptide <200 pmol/l), and these participants had genetic and islet-autoantibody characteristics associated with type 1 diabetes [30].