Caregiver was instructed that blood sugar may be check at different times of the day to get an idea of how well your treatment program is working for you. Typical times to check are before breakfast, before lunch, before dinner, and before bedtime. Sometimes it is helpful to check blood glucose one or two hours after a meal to see the effect of food on your glucose levels. There are certain times when should check the blood sugar more often than usual: During periods of illness or stress, when is suspect that blood glucose is low or high. When there are changes made in the treatment program - such as a change in medication doses, meal plan or activity, when taking new medications.