[RichInOC]

In the sense, for instance, that Type 1 diabetics are addicted to insulin. You’re not taking it so much for your amusement as because you’ll die if you don’t.

[Kaslin]

I would not call them addicted if they have to take insulin. Addiction means you take something without needing it

Addiction

2 : compulsive need for and use of a habit-forming substance (as heroin, nicotine, or alcohol) characterized by tolerance and by well-defined physiological symptoms upon withdrawal; broadly : persistent compulsive use of a substance known by the user to be harmful

Merriam-Webster