What does a diabetic have to do to prevent having high blood sugar?

Eat right & exercise: And take medications as directed. Work w/your doc to find affordable medication(s) w/least side effects that won't drop your sugars excessively causing hypoglycemia (bad for your brain). But start by eating healthy. Study low glycemic index foods which have less tendency to spike your sugars. Typically this means non-starchy veggies. Avoid juices but eat fruit. Don't forget your BP & cholesterol.