Skin stiffness test could prevent diabetic amputations

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * For healthy one: Fasting blood glucose \< 6.1 mmol/L and glycated hemoglobin \< 6.0%, with no history of diabetes; Foot condition: normal appearance of both feet, without wounds, deformities, trauma, infections, or dermatological disorders; voluntary participation in this study with signed informed consent. * For diabetic one: Confirmation of type 1 or type 2 diabetes mellitus as defined by the World Health Organization (WHO) diagnostic standards; Diagnosis of diabetic foot disease\* consistent with the criteria established by the International Working Group on the Diabetic Foot (IWGDF); Voluntary participation in the present study with provision of signed informed consent. Exclusion Criteria: * For healthy one: (1) History of foot surgery, trauma, or fractures resulting in skin scars or irreversible cutaneous damage; (2) Active chronic dermatological conditions affecting skin integrity, such as tinea pedis, eczema, or psoriasis; (3) Vascular diseases of the lower extremities (e.g., arteriosclerosis obliterans) causing muscular or cutaneous atrophy in the feet; (4) Systemic diseases impacting the skin or connective tissues, including systemic sclerosis, rheumatoid arthritis, or vasculitis; (5) Prolonged engagement in heavy physical labor or professional sports leading to abnormal thickening or hyperkeratosis of the plantar skin; (6) Presence of extensive, hyperkeratotic lesions (e.g., calluses, corns) or wounds at the measurement site impairing probe contact accuracy; (7) Inability to cooperate or diagnosed psychiatric disorders; (8) Investigator-determined unsuitability for the study or inability to comply with protocol requirements. * For diabetic one: (1) Uncontrolled severe acute foot infections; (2) Dermatological conditions that interfere with measurement procedures; (3) Irreversible foot skin damage due to non-diabetic etiologies such as trauma or surgical intervention; (4) Coexisting systemic disorders (excluding diabetes) that compromise skin elasticity, including systemic sclerosis, rheumatoid arthritis, or vasculitis; (5) History of above-knee amputation on the measured foot; (6) Inability to cooperate or presence of psychiatric disorders; (7) Investigator-determined ineligibility due to non-compliance concerns or unsuitability for study participation.