I originally published this blog post on October 16th 2007. However, since then this blog has come along way and so has my writing (or at least I hope it has). After re-reading some of my initial posts I identified this one as a post that I could improve a lot. So without further ado, please read the new, improved version of ‘Testing for Diabetes’.
Diabetes is a disease which develops when the cells in your body are no longer getting enough insulin (a hormone which helps your cells convert glucose into energy). There are a number of causes which vary depending upon the type of diabetes. There are also a number of symptoms which can indicate that you are suffering from diabetes. However, the problem with these symptoms is that in a lot of cases they are quite hard to spot. The only way to be certain that you have diabetes is to get yourself tested by a qualified medical practitioner. There are a number of tests available and whilst there is no universal standard by which diabetes is measured, certain tests have become more popular than others. In this article I will discuss 6 tests that can be used to look for diabetes.
1) FASTING PLASMA GLUCOSE (FPG) TEST:- This test measures glucose (the body’s main source of energy) levels in a person’s blood following a period of fasting (not eating). It is one of the most popular diabetes tests but is only given to non-pregnant adults. Therefore, it can be used to test for pre-diabetes, type 1 diabetes and type 2 diabetes BUT it cannot be used to test for gestational diabetes.
You will usually have to fast for eight hours prior to the FPG test. Following your fast a blood sample will then be taken (usually from a vein in your arm). This blood sample will then be used to measure your blood glucose levels and the results will indicate whether or not you have diabetes:
– A blood sugar reading of 99 milligrams per decilitre (mg/dL) or below is considered normal.
– A blood sugar reading of between 100 mg/dL and 125 mg/dL indicates that you have impaired fasting glucose (a form of pre-diabetes).
– A blood sugar reading of 126 mg/dL or above indicates that you have either type 1 or type 2 diabetes. If this is the case you will be given another FPG test and the results of the two will be compared. If the results are consistent your doctor will diagnose you with diabetes and investigate further to determine whether it is type 1 or type 2.
2) ORAL GLUCOSE TOLERANCE TEST (OGTT):- This test measures blood sugar levels following the consumption of a sugary drink containing glucose. Unlike FPG this test can be used to diagnose all forms of diabetes including gestational diabetes (although the methodology does change slightly when testing for gestational diabetes).
If the OGTT is being used to test for pre-diabetes, type 1 diabetes or type 2 diabetes then it acts as an extension to the FPG test. You will be required to fast for eight hours and then have a blood sample taken (as you would for the FPG test). After this your doctor will give you a sugary drink that contains a measured amount of glucose (which should be between 75g and 100g). Following consumption of the glucose your doctor will take blood samples at regular intervals (usually one hour, two hours and three hours after consumption).
If the OGTT is being used to test for gestational diabetes the same procedure will be followed except you will not be required to fast before the test. However, your doctor may recommend that you perform the test first thing in the morning before you have eaten anything.
Whichever type of diabetes the OGTT is measuring, the final blood sample will provide a good indicator as to whether you have diabetes or not:
– A blood sugar reading of 139 mg/dL or below is considered normal.
– A blood sugar reading of between 140 mg/dL and 199 mg/dL indicates that you have impaired glucose tolerance (a form of pre-diabetes).
– A blood sugar reading of 200 mg/dL or above indicates that you have either type 1, type 2 or gestational diabetes. If this is the case your doctor will either diagnose you with gestational diabetes (if the OGTT was to test for gestational diabetes) or investigate further and diagnose you with either type 1 or type 2 diabetes.
3) RANDOM BLOOD GLUCOSE (RBG) TEST:- Unlike the above tests, a RBG test can be performed at any time regardless of when you ate. It can also be performed at home, without the assistance of a doctor, using a glucose meter (a medical device which calculates the approximate level of glucose in the blood). No fasting is required for this type of test. The idea behind this is that although eating does affect blood sugar levels they should not fluctuate hugely if tested at random intervals during the day. This test can be used to test for all forms of diabetes but should not be used as the only basis for diagnosis because there are concerns regarding the accuracy of RBGs.
This test is relatively simple compared with the above tests. You simply prick your finger using a lancing device (a device which pricks your skin in a very controlled way to draw a small drop of blood) then place a single drop of blood on a disposable test strip. You then place this test strip into your glucose meter and it will give you an approximate blood sugar reading. Diagnosis from a RBG is very similar to an FBG with a blood sugar level of 200 mg/dL or over indicating that you have diabetes.
Although this type of test is easier and more convenient than other tests, there are problems with accuracy. Glucose meters are believed to have just 10% of the accuracy of a laboratory test. This is because their main function is to monitor blood sugar levels in diabetics – NOT diagnosing diabetes. Therefore, home RBG tests should only be used to identify the warning signs of diabetes. If this home testing indicates that you may have diabetes do not attempt to self diagnose. Instead, consult your doctor immediately and they will be able to perform further, more accurate tests and give you a proper diagnosis.
4) KETONE TEST:- This test looks for ketones (substances produced by the body when it breaks down fat for energy) in your urine or your bloodstream. The presence of ketones indicates that your body is burning too much fat because; you are not getting enough carbohydrates in your diet OR your body is not using glucose properly. High levels of ketones in your body are a warning sign for all types of diabetes. However, type 1 diabetics are the most likely to experience this because their body produces no insulin (people suffering from gestational diabetes and type 2 diabetes often produce limited insulin). The presence of excessive ketones can also be a sign of diabetic ketoacidosis, a potentially life threatening blood chemical imbalance.
You can test for ketones using either a blood test or a urine test. The blood test is the more accurate but the urine test is the most commonly used because it is more convenient. Blood testing is performed by your doctor and involves a blood sample being taken from your arm. Your doctor will then take this blood sample and test it for the presence of ketones. If ketones are found in your bloodstream your doctor will investigate to determine the cause and then give you further advice.
The urine test can be performed at home using special test strips that are available from your doctor and over the counter at some chemists. It involves urinating in a clean container and then placing a test strip into the urine. If the test strip changes colour there are ketones present in your urine and you should seek the advice of your doctor immediately. They will then be able to investigate further and determine the cause of the ketones in your urine.
5) URINE GLUCOSE TEST:- Urine usually contains little to no glucose. However, when blood sugar levels start to reach 180 mg/dL and above, glucose starts to spill over into the urine. The urine glucose test is not an accurate way to diagnose diabetes because glucose can also appear in the urine when your kidneys get damaged or diseased. However, it does indicate possible diabetes and your doctor will usually follow up with one of the above blood glucose tests if sugar is found in your urine.
To perform a urine test you urinate in a plastic container and then give it to your doctor who will pass it on to the laboratory for analysis. As I mentioned above, the urine test is not used to diagnose diabetes. The chances are that you will be having a urine test for something completely unrelated. If the analysis uncovers glucose in your urine you will then be given further tests for diabetes as a precaution.
6) GLYCOSYLATED HAEMOGLOBIN TEST:- When glucose binds with haemoglobin in the blood, glycosylated haemoglobin is created. The glucose stays attached to the haemoglobin for the life of the blood cell (usually between two to four months). Glycosylated haemoglobin levels increase in people who are not manageing their diabetes properly. Therefore, the glycosylated haemoglobin test can be used to measure a person’s blood sugar levels over the last two to four months and check how effective any diabetes treatments have been.
This test is performed in the same way as a normal blood test. Your doctor will take a blood sample (usually from a vein in your arm) and the levels of glycosylated haemoglobin in this sample are then measured. Your doctor will interpret the results as follows:
– Non-diabetics should have a glycosylated haemoglobin level of between 4% and 6%.
– Diabetics who are treating the condition effectively should have glycosylated haemoglobin of less than 7%.
– Levels of glycosylated haemoglobin above 7% indicate that your current diabetes treatment is not performing effectively and needs to be changed. However, the results will need to be further interpreted by your doctor because other factors can affect your glycosylated haemoglobin levels.
As you can see there are a lot of ways that you can test for diabetes with some being more accurate and others being more convenient. However, the best way to test for diabetes is by consulting your doctor. All the tests discussed above measure the number of ketones or the level of glucose in your body. Whilst high blood sugar and high levels of ketones are a good indicator of diabetes there can be other factors affecting them. For example, your blood sugar levels often rise when you are unwell and ketones may be present in your blood if you are not eating enough. Your doctor has the professional skills to look at these signs, determine the cause and make the call as to whether it is diabetes or not.
Whilst every intention has been made to make this article accurate and informative, it is intended for general information only. Diabetes is a medical condition and this article is not intended as a substitute for the advice of your doctor or a qualified medical practitioner. If you have any concerns regarding any form of diabetes you should seek the advice of your doctor immediately.
Blood Sugar/Glucose Information (Wikipedia)
Blood Sugar Test Results Information (Mayo Clinic)
Diabetes and Ketones Information (Diabetes.co.uk)
Diabetic Ketoacidosis Information (Yahoo Health)
Fasting Plasma Glucose Test (Diabetes Self Management)
Glucose Meter Information (Wikipedia)
Glucose Urine Test Information (Web MD)
Glycosylated Haemoglobin Information (Med Terms)
Glycosylated Haemoglobin Test (Health A to Z)
Haemoglobin Information (Wikipedia)
Impaired Fasting Glucose Information (Wikipedia)
Insulin Information (Wikipedia)
Ketone Test (Web MD)
Oral Glucose Tolerance Test (Web MD)
Screening for Diabetes (Patient UK)
Type 1 Diabetes Diagnosis Information (Health A to Z)
Type 2 Diabetes Diagnosis Information (Health A to Z)