Diabetes is an undetected and silent threat for many people who develop heart disease, according to new research reported on Monday.

Professor John McMurray, of the Western Infirmary in Glasgow, Scotland, said the problem is more widespread than previously realized, highlighting the need for more routine diabetes testing.

Of 43,500 people screened for inclusion into a major heart drug trial - of whom only 20 percent already had cardiovascular disease - approximately one in five had previously undiagnosed type 2 diabetes, McMurray told the annual meeting of the European Society of Cardiology.

And more than one in four additional subjects had impaired glucose tolerance, a pre-diabetic condition that frequently progresses to diabetes.

Type 2 diabetes, which is the most common form of the illness, results from the body’s inability to respond to the action of insulin produced by the pancreas. It is strongly linked with being overweight or obese.

McMurray said the rate of hidden diabetes is alarming and shows that doctors need to do much more to identify and treat the disease.

Diabetes is linked not only to eye, kidney and nerve damage, but also with much worse complications from heart problems and clogged arteries.

McMurray’s findings were based on screening of patients, with an average age of 63 years, for the Navigator study, which is backed by Novartis. It is investigating whether two Novartis drugs, Diovan and Starlix, can reduce heart attacks and stroke and prevent the onset of diabetes in people with impaired glucose tolerance.

Results from the clinical trial, which aims to enroll a total of more than 9,000 patients, are expected in 2008.