SUMMARY

A few rare syndromes have been delineated in which diabetes mellitus is inherited in association with other conditions. This paper describes five patients, including four siblings in one family, who have diabetes insipidus, diabetes mellitus, optic atrophy and deafness (the DIDMOAD syndrome). The parents of both families are normal but are first cousins. All the patients have insulin-dependent diabetes mellitus with a typical juvenile-onset. The onset of diabetes insipidus was insidious and the symptoms could easily have been ascribed to poor control of diabetes mellitus. The importance of diagnosing diabetes insipidus is that all these patients had dilatation of the urinary tract varying from mild hydroureter to severe hydronephrosis and this improved with treatment of the diabetes insipidus. It is suggested that patients with diabetes mellitus and optic atrophy should have regular screening tests for diabetes insipidus since it is likely that they represent cases of the full syndrome with incomplete clinical expression. The occurrence of this rare syndrome in four siblings of unaffected parents indicates that the syndrome is due to a recessive gene, but the pathogenesis is unknown