Scientists have developed a reliable blood test to diagnose diabetes in children at an early stage.

The test can help predict the development of the condition with a reliability of at least 50%.

Previously juvenile diabetes could only be diagnosed early by examining family members of patients suffering from the disease.

The test has been developed by medical researchers at the Sophia Children's Hospital and Rotterdam Erasmus University.

The researchers have found that four out of five patients with juvenile diabetes have tell-tale antibodies in their blood not found in anybody else.

These antibodies are produced in response to the breakdown of cells in the pancreas that produce insulin, the hormone that regulates blood sugar levels.

This breakdown occurs in diabetes patients because of a malfunction in the immune system which causes it to identify pancreas cells as foreign invaders, and to target them for destruction.

The symptoms of diabetes only manifest themselves when more than 80% of the insulin cells have already been destroyed by the immune system.

Blood concentration

By that time, the process of cell breakdown has already been taking place for a number of years.

The new test measures the concentration of the antibodies in the child's blood, which build up long before the symptoms of diabetes become apparent.

In addition to identifying the antibodies, the researchers used a DNA test to determine hereditary susceptibility to juvenile diabetes.

By combining the DNA test and the antibody test, it is possible to determine - with an accuracy of more than 50% - whether a child belongs to the 0.5% of the population who may develop juvenile diabetes.

If only a DNA test were to be used, the accuracy rate would only be 1%.

The new test makes it easier to study the process of juvenile diabetes development and to identify people in possible need of preventive treatment in later years.

A British Diabetic Association spokesman said: "The results of this research look very interesting.

"The earlier that diabetes can be identified in an individual the less harm that is likely to be done by the condition.

"It is vital that research into all aspects of diabetes is given a high priority to try and stem the increasing numbers of people being diagnosed and suffering the long term complications such as blindness and heart disease."