What Causes Aggressive Behavior While Treating Diabetes?
Not due to insulin
Detailed Answer:
I read your question carefully and I understand your concern.
Regarding Insulin injections, they do not produce brain atrophy. They do not cause those symptoms in themselves. The only scenario where they could be involved would be if they excessively lowered his blood glucose which may be manifested with aggressive behavior. But there would usually be other symptoms and also you mention his symptoms as constant, not only occurring after an insulin shot.
As for these changes in character they can have several causes. A brain structural lesion such as a tumor or stroke in certain areas of the brain dealing with behavior may at times be the cause.
Some types of dementia may also have behavior changes as their initial manifestation.
Lastly but perhaps more likely depression may simply be the cause, changes in his health status starting new medications may have contributed to that.
So I would advise a consult with a neurologist or a psychiatrist. If neurological signs are found on physical exam which may indicate a brain lesion than imaging may be required. If there are changes indicating dementia some blood tests might be needed as well. If everything is normal, then as I said depression may be a cause and its treatment may be considered.
I remain at your disposal for other questions.