(February 28, 2008 - Insidermedicine) The way diabetes is currently diagnosed may be based on unreliable research, meaning that the common criteria used to establish the presence of this condition may need to be revised, according to research published in The Lancet.

Here are some facts about diabetes mellitus and how it is diagnosed:

•    Diabetes is a condition in which blood sugar increases as the body's ability to metabolize it is reduced. High levels of sugar in the blood can damage the blood vessels in several organs, affecting these organs' ability to function.

•    In the 1990s, three studies demonstrated that having a blood sugar level of 7.0 mmol/L or more following a fast led to an increased risk for retinopathy – damage to the blood vessels in the retina of the eye – one of the early complications of diabetes.

•    A fasting blood sugar level of 7.0 mmol/L subsequently became the value used to diagnose diabetes, but the studies used to come to this value did not use the most reliable available technique for diagnosing retinopathy.

Researchers from the Centre for Eye Research Australia at the University of Melbourne analyzed data from three studies that diagnosed retinopathy using the most reliable available method, known as multiple field retinal photographs. Nearly 11,500 individuals participated in these studies.

Overall, the researchers found that about 10 to 16% of the general population currently suffers from retinopathy. There was no specific fasting blood sugar value, however, that could reliably separate those who had the condition from those who did not. In fact, more than 60% of the individuals with retinopathy had a fasting blood sugar level under 7.0 mmol/L.

Today's research demonstrates that the current guidelines for the diagnosis of diabetes may not be as reliable as was once believed and may need to be revised.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.