Ummm 'wasn't allowed'? You haven't let them take your insulin off you have you? You may need a quick refresher on being obstinate for what is right and standing up for yourself.
When I go into hospital, I remain in possession and in control of my insulin. The nurses/doctors do not get to take it or my bg test kit away from me. If a nurse asks very politely, I may allow her to hold my insulin vial to read the information on it. If it's an emergency admission or I am non compas mentis, my husband keeps my insulin.
There is NO WAY I am ever going to hand over my insulin to someone who may have had as little as half an hours training on insulin dependent diabetes.