"Can" but not "always". I was prediabetic for years then jumped to diabetic. Drs prescribed metformin. I wanted to try diet first. I changed from cookies, ice cream, and donuts to raw celery, broccoli, carrots, and cherry tomatoes. I eat mounds of those veggies and nuts every day. I dropped 35 pounds and was no longer even prediabetic. Sometimes you just have to live with your genes.