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EDITORIALS: Nicholas J Wareham and Stephen O'Rahilly The changing classification and diagnosis of diabetes BMJ 1998; 317: 359-360 [Full text]

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New diagnostc criteria will influence diabetes prevalence

Jonathan Shaw   (26 August 1998)

New diagnostc criteria will influence diabetes prevalence 26 August 1998
Jonathan Shaw, Research Fellow International Diabetes Institute Send response to journal: Re: New diagnostc criteria will influence diabetes prevalence	26th August 1998 Dear Sir Borch Johnsen et al recently described the effects on diabetes prevalence that would result from a change in the diagnostic criteria for diabetes (1). In an accompanying editorial (2), Wareham and O’Rahilly stated that the changes "would have little effect on the true prevalence of diabetes". This conclusion was not made by the authors of the paper, and is not borne out by their data. In Table 1 of Borch Johnsen’s paper, the total prevalence of diabetes according to new and old definitions is provided. The change in prevalence is given as percentage points. Thus a change from 5% to 7% would be described as an increase of 2 percentage points, though it actually represents a 40% increase in prevalence. When analysed in this fashion, it is apparent that the change in prevalence in the studies presented, ranges from +53% to -40%, and only four out of sixteen studies have a change of less than 10%. Whilst the change was not statistically significant in a number of the individual studies (probably because of the small number of subjects identified as having diabetes), it would not be accurate to imply that the change in total prevalence is not an important issue. Yours faithfully Dr Jonathan Shaw Research Fellow Dr Maximilian de Courten Senior Epidemiologist Professor Paul Zimmet Professor of Diabetes International Diabetes Institute 260 Kooyong Road Caulfield 3162 Australia jshaw@idi.org.au 1. DECODE Study Group. Will new diagnostic criteria for diabetes mellitus change phenotype of patients with diabetes? Reanalysis of European epidemiological data. BMJ 1998;317:371-375. 2. Wareham NJ, O’Rahilly S. The changing classification and diagnosis of diabetes. BMJ 1998;317:359-360.