Not much research has been done to establish any link between insulin therapy and hair loss, and whatever has been done till date is not enough to prove the fact. Conversely, it is insulin resistance – which develops in type 2 diabetes – is known to put a diabetic at a greater risk of maintaining healthy and full hair. https://zovon.com/health-conditions/diabetes/diabetes-and-hair-loss/
I do not think so. The fine capillaries can become damaged in diabetes which could affect hair growth. It is not caused by insulin but the high blood sugars and inflammatory processes.