Diagnostic criteria of glucose intolerance and mortality

In 1997 American Diabetes Association (ADA) Expert Committee approved changing the diagnostic criteria for diabetes. The major change is to lower fasting plasma glucose from 7.8 mmol/l to 7.0 mmol/l for diabetes and did not recommend the use of 2-hour 75 g oral glucose tolerance test (OGTT). The decision by the ADA not to recommend the OGTT has been criticised based on the findings of several recent studies, in particularly those from the Diabetes Epidemiology: Collaborative Analysis of Diagnostic Criteria in Europe (DECODE) and in Asia (DECODA) Studies. These studies have reported that only 29% of all newly screened diabetic subjects qualified for diabetes on both the fasting and the 2-hour glucose criteria in European and 37% in Asian populations. It has now been clearly shown that elderly and less obese patients are more likely to have diagnostic 2-hour values, whereas fasting hyperglycaemia is more common among obese subjects. Analysis of the prospective DECODE data showed that elevated 2-hour glucose was a better predictor of mortality from all-cause and from cardiovascular and non-cardiovascular diseases than elevated fasting glucose alone. The largest absolute number of excess deaths was observed in subjects with impaired glucose tolerance (IGT), especially in those whose fasting glucose was normal.