The Joint British Societies' algorithm for the diagnosis of diabetes mellitus in routine clinical practice

Summary The diagnosis of diabetes mellitus (DM) requires a logical approach to identify new cases while not subjecting every patient to an oral glucose tolerance test (OGTT). The Joint British Societies’ (JBS2) have recommended an algorithm for the diagnosis of DM. We retrospectively obtained the results of 100 OGTTs requested by primary care physicians, along with previous glucose results and whether the patient was fasting or not with a view to determining how many OGTTs could be avoided by following the recommended algorithm. We found that 47% of the OGTTs could have been avoided, of which the algorithm would have identified all but 4%. Two cases of DM and eight cases of impaired glucose tolerance (IGT) would have been missed. We conclude that following the JBS2 algorithm for the diagnosis of DM will significantly reduce the number of OGTTs, with only a few patients with IGT or DM being missed when such a policy is used.