The World Health Organization estimates that at least 180 million people around the globe have diabetes. It says the number could double in 20 years.  The most commonly used test for diabetes is a blood test given after hours of fasting, and then more testing after a patient drinks a sweet tasting liquid.  Now, however, diabetes experts are calling for wider use of a different blood test that may be more convenient and reliable. 

Nurse administers a blood test for patient

Many people do not realize they have Type 2 Diabetes until it has already led to other health problems, such as cardiovascular disease, damage to the eyes and kidneys.

"While they have the diabetes and don't know it, they can't treat it.  They can't prevent the damage it's doing to their blood vessels, their eyes, their kidneys," said Dr. David Nathan from Massachusetts General Hospital in Boston.

The most common form of diabetes screening requires patients to follow a restricted diet before they fast for eight to 16 hours.  Then blood is drawn at least two times.  But this test measures the patient's glucose level only at the time the blood is drawn.  

Dr. Alvin Powers of Vanderbilt University Medical Center in Nashville, Tennessee, says other factors can influence the readings. "Things like exercise, your diet, whether you've been ill recently can influence blood glucose and require that that test be repeated," he said.

Now doctors are being urged to give their patients a different test.  The A1c blood test has been in existence for years.  

Recently, however, a group of international experts from three major medical associations called for the A1c test to be the standard.  There is no fasting involved, it is more convenient and measures a patient's blood sugar level over a two to three month period.

The A1c test measures glucose that has attached itself to hemoglobin, a protein in red blood cells.  The amount of glucose that combines with hemoglobin is proportional to the total amount of glucose in a person's system.  

"It gives a much more accurate measure of whether someone actually has diabetes," Dr. Nathan said.

Diabetes experts say the A1c test might identify patients early before it is too late to reverse the illness.