Even if you are on diabetes, it doesn't mean that you are limited to eating almost nothing . In fact some people eat certain diets foods in order to reduce the risk of diabetes( if you don't have one), have your A1C reduction, and more. The thing thats makes your blood sugar rise is cards so set a range of carbs you want to stay n for each meal. Like from 10 carbs to 50 carbs.

Excersise is important so you can stay fit and be healthy. But its more important for diabetics because when diabetics active, diabetics' cells become more sensitive to insulin so it works more effectively.