It has been mentioned that here in the UK it is only necessary to inform the DVLA if you are a Type 1 diabetic on Insulin, well if you look closer into this you will find that a law has been approved and is on the British Statute Book that diabetes is one of a number of conditions in which the UK driver needs to confirm with the DVLA and seek approval before being officially allowed to drive here in the UK.
What most people don't realise is that this statuary law also applies equally to a Type 2 diabetic on any medications which might result in them going Hypo, so it's not only type 1's that are effected by this ruling. Generally a Type 2 is approved to drive here in the UK but the Law being the Law can and is sometimes enforced when the authorities see appropriate to do so. For this reason any diabetic whether Type 1, Type 2 or whatever other type of diabetes (excluding Gestational diabetes) is required to obtain the appropriate authorisation from the DVLA.
In the case of a Type 1 on INSULIN the applicant will be asked to provide their GP or Specialist's name so that confirmation is then sought that they have been free from going Hypo for many months and also have good control of their diabetes, and in the case of Type 2's (those not on INSULIN) they are sent a different form where having listed their diabetic medications they are then permitted to sign their own self-declaration stating that in their own opinion they are safe to drive.