How do you keep a normal blood sugar level during the day and night?

Diet ; Exercise. This depends on whether you are diabetic or have Insulin resistance. Assuming you are in good health, eating lean protein and low glycemic carbohydrates in small portions together with exercise are key to maintaining stable blood sugar levels.
Diet and exercise. Eating a well balanced diet with a low glycemic index and regular aerobic exercise will help in keeping glucose in the normal range. If you have pre-diabetes, metabolic syndrome or are overweight, it is imperative to loose weight.