Knowing the level of glucose in your blood is useful for when you are trying to control your diabetes. It can help to maintain day-to-day control, detect hypoglycaemia, assess control during any illness, and helps to provide information that can be used in the prevention of long term complications. People with diabetes will also have tests to check longer term blood glucose levels called glycated haemoglobin (HbA1c) or fructosamine tests.