There are several tests that can be used when diagnosing diabetes. Some give crude results, while others are really more specific.
Urine tests are often used when you go to your doctor for a general check-up. It is often the case that if you go to the doctor to get an idea of your general health at certain stages of life, they will give you a blood test that checks for cardiovascular disease markers such as cholesterol levels, check your blood pressure and also test a urine sample for glucose. Urine doesn’t usually contain glucose, but if blood glucose levels get particularly high, it can begin to escape via the kidneys and exit the body via the urine. The problem with this test, however, is that it just gives a suggestion that there may be a problem, rather than anything specific. It gives the clinician the impetus to do more testing and is seen as a non-invasive starting point. It may well be the case that the patient is diabetic or pre-diabetic, or there may be a very simple benign transient cause for this rise in glucose, such as an Easter egg-eating marathon! It can alert practitioners to a potential problem in an unthreatening and easy way, but doesn’t really tell them much more than there is a lot of glucose present currently.
Another relatively common test is the oral glucose tolerance test. This basically measures how the body deals with glucose. The patient is asked to fast for eight to 12 hours before the test. Upon arrival they have a base sample of blood taken. This shows glucose levels following a period of fasting. In healthy individuals, the base level of glucose should be less than 6.1mmol/L. A level of above 7.0mmol/L is believed to confirm a diagnosis of diabetes. They are then given a standard dose of glucose. After two hours, a further blood sample is taken to measure the amount of glucose present in the blood, in order to determine how effectively the body has dealt with it. In a healthy individual, blood glucose two hours after consuming the standardised dose should be below 7.8mmol/L. A level of between 7.8mmol/L and 11.1mmol/L indicates an impaired glucose tolerance. A level above 11.1mmol/L again is diagnostic of diabetes.
There is one test that has now become a bit of a benchmark. It is thought that this test gives the best long-term picture of an individual’s glucose levels. This is measuring the level of glycated haemoglobin, a type of haemoglobin that is formed upon exposure to glucose. Glycation is basically a binding between a protein and a sugar, in this case haemoglobin and glucose. It is normal to find some glycated haemoglobin, but the longer blood glucose remains elevated the higher the amount. So, individuals that are at the point where they are getting notably insulin resistant and whose blood glucose levels are getting and staying very high will have a far higher level of glycated haemoglobin. If this number is higher, then the individual would have had raised glucose for longer, giving a more accurate indication that there are pathological changes rather than transient fluctuations. Normal healthy individuals should have a level of 5.7 per cent or lower. A level of up to 6.4 per cent is considered to show insulin resistance or pre-diabetic stages. A reading of above 6.5 per cent is believed to be indicative of diabetes.