INS and type 1 diabetes mellitus: Our study of type 1 diabetes patients had several strengths—large size; information to allow analyses by age at diagnosis of diabetes (not published for any other cohort, except for one publication on a two‐way split of ages for three cancer sites10); high completeness of follow‐up; longer follow‐up than any study previously; information on cancer mortality as well as incidence; and restriction to insulin‐treated patients.