SUMMARY In diabetics, foot deformities are risk factors that increase the risk of amputation as a result of developing ulcers. However, knowledge of the influence of plantar stiffness is still limited. The main objective was to describe connections between the degree of stiffness of the ankle, atypical amputation, and the Foot Posture Index (FPI). METHODS 62 diabetic patients, 58 with type 2 and 4 with type 1 (average age 63.35 years) were included. Records of foot deformities were included; A range of motion test of the ankle joint was used to determine the degree of stiffness. An exploratory analysis of the association of foot position and the degree of rigidity was performed. RESULTS The dorsal flexion range of the ankle was 9.6 ± 5.1 0, 13.8 ± 5.9 0 and 17.2 ± 6.5 0 and 20.5 ± 6.8 0 to 45, 67, 89 and 111 N respectively in the amputated feet., And 14 patients (22.58%) had a high level of pronation of IPF with an average value of 3.7 ± 2.629, CI (3.032.-4.367) in amputated feet compared to non-amputees. We use the device “Iowa ankle range of motion” (IAROM) to determine the differences in ankle stiffness. Proper IPF was associated with the presence of amputation and an increase in stiffness CONCLUSIONS There was an increase in the degree of limitation of movement of the ankle, as a greater force was applied. Comparing FPI between the groups, there was a higher frequency of prone feet in the group of amputees