INS and type 2 diabetes mellitus: In contrast, those who were insulin deficient but were incorrectly classified by UK guidelines as having type 2 diabetes commenced insulin treatment more quickly than those correctly classified as having type 2 diabetes (time to insulin from diagnosis 12 months [IQR 2–18 months]) versus 84 months [IQR 42–138 months], P <0.001), had lower BMI (22.5 kg/m2 [IQR 21.1–26.3 kg/m2] versus 28.1 kg/m2 [IQR 25.4–33.3 kg/m2], P <0.001), and were younger at diagnosis (44 years [IQR 35–56 years] versus 51 years [IQR 43–59 years], P= 0.014).