The increased vulnerability of urban populations to disease and the fact that tell-tale symptoms can now be picked up much earlier have led doctors to adopt revised standards for diagnosing diabetes.

According to the revised standards, fasting plasma glucose values (blood sugar levels taken when the person is on an empty stomach) of 140mg per decilitre (mg/dcl) are no longer considered safe. Instead, only those having plasma glucose values of 110mg/dcl can now be called ``non-diabetic''.

Those falling in the category of 110mg-125mg plasma glucose are now labelled as having Impaired Glucose Tolerance (IGT). This makes them strong candidates for diabetes, especially, if other factors like a family history of diabetes, obesity or a sedentary lifestyle are also present. This segment of the population, the experts believe, needs to be targeted immediately to reverse its chances of developing diabetes.

``Considering the fact that very early diabetes can be managed even with certain lifestyle changes alone, we now label those as diabetics who have a plasma glucose reading of 125mg and above,'' says Dr Mandeep Bajaj, a senior diabetologist attached with the Capital's Indraprastha Apollo Hospital. ``They are advised (to go for) aggressive blood glucose control with lifestyle changes or its combination with drugs.''

Incidentally, the American Diabetes Association had revised the above criteria during its annual meeting in June 1997. But endocrinologists and diabetologists here took note of it only last year when the World Health Organisation's expert committee on diabetes formally modified it.

General practitioners and the diagnostic experts at the laboratories, however, are still largely unaware of the revised criteria. Result: A large segment of the population is not diagnosed as diabetic or as fast inching towards it.

More and more studies are revealing that the onset of diabetes-related complications, especially its effects on the heart and its blood vessels, start at a threshold blood sugar level (of more than 110 mg). That's why the level between 110 mg/dcl and 125 mg/dcl is now labelled as IGT.

According to Dr N. Kochupillai, professor of endocrinology at the All India Institute of Medical Sciences (AIIMS): ``IGT, or the pre-diabetic condition, is the leading cause of heart disease and pre-mature deaths in India. Long before diabetes actually sets in, the IGT causes a gradual degeneration of the blood vessels, leading to the heart disease.''

Last year, Bajaj, along with Dr Carol J. Levy of the division of endocrinology, diabetes and metabolism at Mount Sinai Medical Centre, New York, was involved in a comprehensive study on diabetes, conducted by his alma mater, Harvard Medical School, Boston.

The experts underlined that a considerably lower threshold of blood sugar can now affect the vessels of the heart and, so, it was important to catch the patients earlier.

The earlier standard of diagnosing diabetes, that of 140 mg/dcl of fasting plasma glucose, was fixed apparently due to fears that prescribing blood sugar control at lower levels could expose people to the risk of hypoglycemia -- a condition in which blood sugar drops lower than the required levels.

The study, involving people of Asian origin settled in UK, concluded that those having type-II diabetes were at a much lower risk for hypoglycemia than those suffering from type-I or juvenile diabetes (which is present by birth and requires insulin therapy from day one).

``Though IGT is just a pre-cursor to diabetes, its effect start on blood vessels at a very early stage. Before one knows it, atherosclerosis (blockage of arteries) sets in due to the interplay of blood sugar and cholestrol and resultant lipid abnormalities. This is what mostly causes heart disease among Indians,'' says Dr S.K. Wangnoo, the country's leading endocrinologist and the founder member of Delhi Diabetic Forum. For a country like India that's facing the threat of a diabetes epidemic, the revised standards are of particular significance. Not only are they a warning, they also give health planners a chance to catch potential diabetics much earlier.

``We need to view the development in a positive light,'' Dr Bajaj says, assuring that reverting to a healthy diet and regular exercises could prevent the epidemic. According to Dr Kochupillai, the answer is to go back to our traditional lifestyle and shun all fast or ``cafeteria'' food that has become a trigger for a host of health problems.