Randomised controlled trials (RCTs) and non-randomised studies (including follow-up studies) that assessed the effectiveness of insoles for the prevention of diabetic foot in patients free from ulceration were eligible for inclusion in the review. Eligible participants had to present with type 1 or type 2 diabetes and neuropathy. The primary outcome measure of interest was time to ulceration. Eligible studies had to include one or more of the outcomes: ulceration, cost, pressure measurement and patient-based response.
The included studies assessed different custom-made insoles that included plastazote-based casted insoles, magnetic insoles, ethylene-vinyl acetate (EVA) and polyethylene foam insole and ridged (TL-2100 graphite) casted insole. Where reported, included participants were recruited from university/teaching hospitals, an orthotics laboratory and private practices. Specific patient characteristics varied between the studies with respect to level of detail reported, type of diabetes and risk of ulceration; further details were reported in the review. Patient age ranged from 59.6 to 68.9 years. Duration of diabetes ranged from 11.6 to 7.5 years. Inclusion criteria for the studies varied. Studies were carried out in USA, Italy and Germany. Reported outcomes included ulcer relapse rate, reduction in peak pressure, reduction in neuropathic pain, contact surface area and quality of life.
Two reviewers independently assessed the studies for inclusion. Discrepancies were resolved through discussion (the rate of agreement was 97%).