Limited joint mobility in the hand is a common manifestation of diabetes with the reported prevalence in insulin-dependent diabetes varying between 8 and 43%. Sixty-two subjects were studied in three groups (controls, diabetic patients without foot problems, and diabetic patients with neuropathic ulceration) to determine whether similar changes occur in the joints of the foot and to examine any possible relationship with neuropathic ulceration. There was a significant impairment of mobility in the range of motion of the sub-talar joint in diabetic patients with ulcers when compared with controls (p = 0.0001) or with the other diabetic patients (p = 0.004). There was a significant correlation between sub-talar range of motion and mobility in other joints of the foot such as at the hallux (r = 0.59, p less than 0.001), or with mobility of the 5th finger (r = 0.41, p less than 0.01). There was also a significant association between the clinical presence of limited joint mobility in the hand, Dupuytren's contracture, and mobility of the sub-talar joint (p less than 0.05). Furthermore, impairment of mobility of the sub-talar joint was greatest on the affected side in those diabetic patients with neuropathic ulceration (p = 0.029). We conclude that the syndrome of limited joint mobility also affects the joints of the feet of diabetic patients and may predispose to ulceration in susceptible neuropathic feet.