Yes, if pen/vial. If a person truly is 'insulin dependent' then yes, they will need Insulin all the time. The longest lasting insuling from vials or pens lasts 24 hrs, so a person using these will need a minimum once daily injection. If the person has an Insulin pump providing Insulin continuously thru a small tube in the subcutaneous tissue, they don't need injections, but need to change tube every 3 days.
Yes. If you are Insulin dependent, you will need Insulin to control your blood sugar.