Diabetes Go

Pets and diabetes, can anyone help?

My friend’s cat was old and in bad health, it seemed to just hit him. They took him to the vet and he had renal failure and diabetes. The same thing happened to my grandmother’s cat today… and she was put down. I have 3 cats of my own… and I was wondering, is diabetes a VERY common thing for old cats or is there a problem with their diet/ lifestyle that is causing it? What can I do to prevent my cats and dogs from developing diabetes?