Other ailments that have succeeded include diabetes (Hennessy 1989) and sleepwalking (Burgess 1991).
In cases like this it could be seen as strange that a defendant has to plead that they are legally insane instead of being able to use non-insane automatism. The reasoning behind this is that if the cause of a defendant's defect of reason is internal they cannot use the defence of automatism and if the cause is external they cannot use insanity. The problems with this are easiest to see in cases where diabetics who have gone into an automatic state. If they suffered hyperglycaemia then they can use the defence of insanity, if they suffered hypoglycaemia then they can use automatism. The defences are different even though the effects are the same. This is because hypoglycaemia is technically not caused by diabetes but either insulin or the defendant not eating enough, as seen in Quick 1973. .
If a defendant knows the "nature and quality of the act" they committed and they understand that it is legally wrong then they cannot use the defence of insanity, even if they have a disease of the mind. An example of this is Windle 1952 when, after killing his wife following her constantly speaking of killing herself, the mentally ill defendant told police "I suppose I'll hang for this." His declaration proved that he understood the nature of what he had done and that it was wrong. He was therefore found guilty, although today he may have been able to use the defence of diminished responsibility to lower his conviction to manslaughter. .
If a defendant is found not-guilty by reason of insanity then a judge can impose either a hospital order, a supervision order or an absolute discharge. If the defendant is charged with murder, however, the judge must impose an indefinite hospital order. Up until 1991, before the Criminal Procedure (Insanity and Unfitness to Plead) Act, a judge would have to impose a hospital order even though it wasn't suitable for defendants with physical conditions like diabetes.