The blood sugar levels are tested in the morning, before meals and at night to determine whether the dose rate of the rapid-acting insulin acting as the basal is suitable at different times of the day. The post-meal blood sugar test result indicates whether the rapid-acting mealtime insulin, i.e., bolus is suitable.
The evening/morning paired tests reveal the correct overnight dose rate of basal. If you don’t use a sensor, you should occasionally test your blood sugar approximately 4 hours before you wake up to check the nightly level of blood sugar.
The pre-meal/post-meal tests establish the right insulin-to-carbohydrate ratio at different times of the day, like in the MDI treatment.
Monitor your blood sugar more frequently after replacing the cannula, cartridge or catheter in order to quickly detect any potential issues.
In practice, modern insulin pumps are used together with a glucose sensor, or the pump itself includes a sensor. However, it is necessary to check your blood sugar either to calibrate the sensor or in situations where the sensor reading is not reliable.