Diabetes Mellitus is caused by a reduced or absent production of insulin by the pancreas.
A deficiency of insulin causes the level of glucose in the blood to rise and can, if untreated, lead to coma.
One of the first symptoms is thirst and the need to pass water more frequently.
By using diet restrictions, insulin and other drugs, doctors try to lower the blood sugar level.
To assess the effectiveness of therapy, doctors check the urine for sugar and also the blood Glucose levels after fasting and after meals. These tests inform the doctor if the blood sugar level is under control at the time of the test.
The Glycosylated Haemoglobin test gives an idea how well the blood sugar level has been controlled in the previous 6-8 weeks - the approximate half life of red blood cells.
Haemoglobin is the oxygen carrying component of red blood cells. A small part of it is bound to glucose to form glycosylated haemoglobin. In normal people 3-8% of haemoglobin is glycosylated, but in people with uncontrolled diabetes the levels of glycosylated haemoglobin can be any where between 8-20%. | 
Phlebotomy
