Blood glucose test in diabetes. Man dips blood from his finger onto a glucose test strip, to test his blood sugar level. The yellow lancet which he used to prick his finger is seen. This is the BM Test 1-44, which measures blood glucose from 1-44 mmol per litre. The blood reacts with the 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. Diabetes mellitus is a carbohydrate metabolism disorder, in which unused sugars accumulate in the blood and urine. Raised levels of blood glucose must be controlled, both by a strict diet and the use of insulin injections.