Mick, to be more specific, this is what happens when you take too much insulin...

Your blood glucose will drop to the point where you will start to feel dizzy, sweaty and shakey. These are the first symptoms one will experience when using too much insulin and not consuming enough carbohydrates. Other symptoms such as blurry vision and headaches can also occur but this is not where it ends.

If you get to that point and don't consume carbs you can fall into a diabetic coma which can lead to lack of oxygen to the brain which leads to brain damage. This drug is quite nasty if you don't respect it.

I believe your friend is OK now, but I would still see a doc to ensure there is nothing else wrong.

People who want to leave this world in such way need counciling and must be under constant supervision. Please help your friend before he does something stupid again.

-Gear