Eighteen of 66 Black patients with type I (insulin-dependent) diabetes mellitus had limited joint mobility (LJM). The presence of LJM was related to the duration of diabetes but not to the total daily insulin dose or to the glycosylated haemoglobin percentage. The incidence of diabetic retinopathy was not increased in those patients with LJM, but this was probably because of the relatively small study population and the relatively short duration of diabetes in this group. Short stature was a feature of this group of patients.