How many years is a person expected to lose if they have diabetes before 15?

It is difficult to come at the exact figure but if you can manage Diabetes then I don't think you can lose any years attributable to diabetes. Yoga is the best way to manage diabetes. Diabetes is an ailment that prevents the production/absorption of insulin in the body. The causes for diabetes are stressful lifestyle, genetic disorders, hereditary, etc.

The yogic practices which are effective in tackling this condition are Sun Salutations (Surya Namaskara), Churning the Mill (Chakki Chalanasana), Rowing the Boat (Nauka Sanchalanasana), Back Stretching pose (Paschimottanasana), Fish pose (Matsyasana), Half Spinal Twist (Ardha Matsyendrasana), Frontal Brain Cleansing Breath (Kapalbhati Pranayama) and Short Intestinal Wash (Laghoo Shankhaprakshalana).