Blood glucose test in diabetes. Man's hands hold a glucose test strip against a scale, to test his blood sugar level. The test is negative. A yellow lancet was used to prick the finger, and place a drop of blood on the test strip. This is the BM Test 1-44, which measures blood glucose from 1-44 mmol per litre. The blood reacts with two coloured squares at the tip of the test strip, and depending on the level of blood glucose changes from yellow to black, white to dark blue. Here, the reading between 4-7mmol per litre is normal; a reading of 11mmol per litre or above is diabetic. In diabetes mellitus, raised levels of blood glucose must be controlled by insulin injection.