MISUNDERSTANDING IN THE CLASSIFICATION OF DIABETES-MELLITUS - WHATS IN A NAME

To assess whether physicians, residents, medical students, hospital di agnosis coders, and patients properly use the designations insulin-dep endent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mel litus (NIDDM) that were established by criteria of the National Diabet es Data Group, we reviewed clinic and hospital records and administere d questionnaires. Although essentially all cases of true IDDM were ide ntified as such and most cases of NIDDM not requiring insulin therapy were correctly identified by all groups, patients with NIDDM on insuli n therapy were misidentified as having IDDM by 38% of residents in int ernal medicine clinics and 68% of primary care and surgical subspecial ty residents. On a survey, of 22 patients with NIDDM on insulin therap y, 17 (77%) considered themselves to have IDDM. Thus, patients who hav e NIDDM by the established criteria who are on insulin therapy are com monly mislabeled as having IDDM. We present an approach for dealing wi th this problem by adapting nomenclature focusing on insulin deficienc y and resistance. It would probably also be helpful to separately iden tify the subset of patients with 'insulin-deficient diabetes'' who are ketosis-prone. It is important to use immunologic profiling (islet ce ll antibody testing) and insulin sensitivity or deficiency testing (C- peptide levels).