The new classification of diabetes mellitus and IGT: a critical approach

In 1999 WHO published the new recommendations for diagnostic criteria for diabetes. The same publication introduced several new categories including the first proposal for diagnostic criteria for the metabolic syndrome. Also, WHO established a new category labelled "impaired fasting glycaemia", and thereafter this new group and the already established impaired glucose tolerance was combined as a common entity labelled "impaired glucose regulation".--These recommendations from WHO followed a decision in the American Diabetes Association to lower the diagnostic plasma glucose threshold for diabetes in the fasting state from 7.8 to 7.0 mmol/l and to use fasting values as the diagnostic test for diabetes. The suggested changes in the diagnostic criteria will include a new group of individuals as having diabetes, while others may be left undiagnosed if fasting glucose values are used as the only diagnostic criteria. The consequence of this has been analysed by several groups including the collaborative European activity (the DECODE-study).--This review summarises the findings. One major problem is that if fasting glucose values are used as the only diagnostic criteria in screening for diabetes, approximately one third of the diabetic individuals will be left undiagnosed. Furthermore, this group is the group of diabetic patients that have the highest mortality from cardiovascular disease and stroke, and the group with the worst cardiovascular risk profile compared to individuals with elevated fasting glucose values alone. This observation raises the need for a continued use of the oral glucose tolerance test in selected groups.