Blood glucose testing is an important part of diabetes care. This can be done with a portable electronic device, called a blood glucose meter, using a small drop of your blood, or with a device, called a continuous glucose monitor (CGM). 

CGM devices use a sensor inserted under the skin to measure blood glucose levels every few minutes and can assist people with Type 1 to manage their glucose levels.  

Any form of testing should be used as a tool to help you and your doctor adjust your medication, or your diet and exercise regime, so keep records.

Reference: www.mayoclinic.org/diseases-conditions/diabetes/in-depth/blood-sugar/art-20046628