You need to take our Defeat Diabetes^® Screening Test (if you haven't already) as a first step in the detection process.  If your test results there indicate you need more testing, here is a primer to help you understand the different types of tests, what they mean and how they are performed.  We trust you will find this information helpful.

Please note that many of the blood tests described below require specific preparation for optimum performance, such as a special diet or the suspension of certain medications. To get the most accurate results, be sure to closely follow the instructions of your healthcare provider before taking any diagnostic test. This list is not all-inclusive, and other blood tests may be prescribed based on your specific medical history.

High Blood Glucose Levels - The "Measuring Tool" for Determining Diabetes

Doctors diagnose diabetes on the basis of too-high levels of glucose in the
blood. If you have diabetes, your blood glucose levels rise because of the
foods you eat. Foods have little effect on blood glucose in people without
diabetes. Normally, insulin, a hormone that is made in the pancreas, allows glucose to enter your body's cells and be used as fuel. Insulin is the main
tool your body uses to lower your blood glucose level.  People with diabetes can have insulin deficiency which means (they make too little insulin) or insulin resistance, which means they don't respond well  to insulin. In people with diabetes, insulin is not doing its job, so their body's glucose can't get into their cells and be used for energy. Instead, their unused glucose builds up in their blood and passes through the kidneys if the glucose level becomes high enough. The extra glucose causes frequent
urination, which in turn leads to thirst (this is the body's way of making up for the fluid lost in urination).

Different types of diabetes tests
 
What Urine Tests Measure                                                                           

High urine glucose levels give doctors a clue that something is wrong. But
urine tests are not a good way to diagnose diabetes. Urine tests are not as
accurate as blood tests. And the level of blood glucose needed to make
glucose appear in the urine is different for each person. Your glucose level
could be high, yet high levels of glucose may not appear in the urine. So in
diagnosing diabetes, doctors measure glucose in the blood.

Urine tests are a very useful way to measure ketones, substances that build
up when blood glucose is very high.

Blood Tests

The goal of blood glucose tests is to find out whether you have a very large
amount of glucose in your blood. There are two types of tests: screening
tests and diagnostic tests. Screening tests are performed on people who have
no symptoms of diabetes. On the other hand, diagnostic tests are done to
confirm a diagnosis that is already suspected from the patient's symptoms.
Screening tests are fast, easy to perform, and cheap. (Health fairs often
offer screening tests, for example.) Screening tests require as little as a                      
drop of blood from your fingertip and take only a minute or two to complete.
Most doctors don't screen everyone for diabetes during regular checkups. The chance of finding the disease in most people is just too low. But screening tests are useful for people who may be at risk for developing diabetes.

People at risk include:

- blood relatives of people with diabetes
- women who have had gestational diabetes or who have had babies weighing 9
pounds or more at birth
- African Americans, Hispanic Americans, Asian Americans, Native Americans,
and Pacific Islanders
- people with a condition known as impaired glucose tolerance or impaired
fasting glucose (see below)
- people with high blood pressure or very high blood cholesterol or
triglyceride levels
- people who are obese
- people 45 years or older

Pregnant women should be screened for gestational diabetes (diabetes that
starts during pregnancy) between the 24th and 28th weeks if they are 25
years of age or older, less than 25 years of age and obese, if they have a
family history of diabetes (parent or sibling), or if they are a member of
an ethnic/racial group at high risk for diabetes (Hispanic-American, Native
American, Asian-American, African-American, or Pacific Islander).

If you are 45 years or older, have your blood glucose level checked every 3
years. If you have risk factors, you may need to be tested more often.
For diagnostic tests, the doctor's office draws samples of blood from a vein
and sends them to a laboratory for analysis. Different types of diagnostic
tests are used to diagnose diabetes-fasting plasma glucose, random plasma glucose, and oral glucose tolerance tests. When you get your test results, ask your doctor to explain them to you. Comparing your test results with those of family or friends may confuse or alarm you. You may not have had the same type of test, so your results could have a completely different
meaning.

Fasting Plasma Glucose Test

The fasting plasma glucose test used to be the preferred way to diagnose diabetes.
It is easy to perform and convenient. After you have fasted overnight (at
least 8 hours), a single sample of your blood is drawn at the doctor's
office and sent to the laboratory for analysis.
Normal fasting plasma glucose levels are less than 100 milligrams per
deciliter (mg/dl). Fasting plasma glucose levels of more than 126 mg/dl on
two or more tests on different days indicate diabetes.

Random Plasma Glucose Test

Sometimes, random blood samples (if taken shortly after eating or drinking)
may be used to test for diabetes when symptoms are present. A blood glucose
level of 200 mg/dl or higher indicates diabetes, but it must be reconfirmed
on another day with a fasting plasma glucose or an oral glucose test.

Oral Glucose Tolerance Test

With the oral glucose tolerance test, you must fast overnight (at least 8
but not more than 16 hours) and go to your doctor's office or the laboratory
in the morning. First, your fasting plasma glucose is tested. After this
test, you receive 75 grams of glucose (100 grams for pregnant women).
Usually, the glucose is in a sweet-tasting liquid that you drink. Blood          
samples are taken up to four times to measure your blood glucose.
For the test to give reliable results, you must be in good health (not have
any other illnesses, not even a cold). Also, you should be normally active
(for example, not lying down as an inpatient in a hospital) and taking no
medicines that could affect your blood glucose. For 3 days before the test,
you should have eaten a diet high in carbohydrates (150-200 grams per day).
The morning of the test, you should not smoke or drink coffee.
The oral glucose tolerance test measures blood glucose levels five times
over a period of 3 hours. In a person without diabetes, the glucose levels
rise and then fall quickly. In someone with diabetes, glucose levels rise
higher than normal and fail to come back down as fast.

People with glucose levels between normal and diabetic have impaired glucose
tolerance (IGT). People with IGT do not have diabetes. Each year, only 1-5%
of people whose test results show IGT actually develop diabetes. And with
retesting, as many as half of the people with IGT have normal oral glucose
tolerance test results. Weight loss and exercise may help people with IGT
return their glucose levels to normal.
If your values are abnormal, you will need to have another test-preferably
the fasting plasma glucose test.

Glucose tolerance tests may lead to one of the following diagnoses.

Normal response. A person is said to have a normal response when the 2-hour
glucose level is less than 140 mg/dl, and all values between 0 and 2 hours
are less than 200 mg/dl.

Impaired glucose tolerance. A person is said to have IGT when the fasting
plasma glucose is less than 126 mg/dl and the 2-hour glucose level is
between 140 and 199 mg/dl.

Diabetes. A person has diabetes when two diagnostic tests done on different
days show that the blood glucose level is high.

Gestational diabetes. A woman has gestational diabetes when she has any two
of the following: a fasting plasma glucose of more than 95 mg/dl, a 1-hour
glucose level of more than 180 mg/dl, a 2-hour glucose level of more than
155 mg/dl, or a 3-hour glucose level of more than 140 mg/dl.
                                                                                                                     
In diagnosing your diabetes, your doctor needed test results. But test
results are just part of the information that goes into the diagnosis of
diabetes. Your doctor also took into account your physical examination,
symptoms, and medical history to decide to test.

The Blood Test With a Memory

When you've been diagnosed with diabetes, your doctor may order another type
of blood test called glycated hemoglobin. This test is easy to do during
routine office visits. GHb lets the doctor take a backward look at your
diabetes control.
Hemoglobin is the protein in red blood cells that carries oxygen. GHb forms
when glucose in the blood attaches to the hemoglobin. Because blood cells
stay in circulation for 2-3 months, GHb level is a good measure of a
person's average blood glucose level over the previous 2-3 months.

The GHb test requires only one sample of blood, which can be taken at any
time of the day, even right after a meal.

Although a high GHb almost always means IGT or diabetes, people with IGT or
diabetes can have normal GHb levels. So the GHb test is not used to diagnose
diabetes. Doctors use it to monitor blood glucose control.

Type 1 or Type 2?

After the diagnosis of diabetes, the doctor will take many factors into
account to determine which type of diabetes you have. In general, people
with type 1 are diagnosed before they are 30 years old, are lean, and have
had diabetic ketoacidosis (which sometimes leads to a coma) or have high
levels of ketones in their urine. People with type 2 are most often
diagnosed when they are over 30 and obese. They usually do not have urine
ketones. Of course, there are exceptions to these categories. Whatever type
you have, the goal of treatment is to get your blood glucose levels as close
to normal as possible

                                                         
References:                                                                                                                   
http://www.defeatdiabetes.org/
http://www.healthtalk.com/den/toc/basics/02.html
http://www.diabetes.org