Background: Individuals with diabetes mellitus (DM) are susceptible to balance, gait and cognitive impairments. Importantly, diabetes affects executive function, a set of cognitive processes critical to everyday cortical function and mobility. Reduced executive function is a risk factor for falls in people with DM. Dual-task testing, the completion of two tasks at once, enables the examination of the cognitive-mobility relationship. A synthesis of the literature on the effects of dual- task testing on the balance and gait of individuals with DM has not been performed.Objective: To systematically review the literature on the effect of dual-task testing on balance and gait in people with DM. Methods: Databases EMBASE, CINAHL, MEDLINE, PsycINFO, Scopus and Web of Science were searched (inception-April 2020). Inclusion criteria: participants were adults with a diagnosis of DM, instrumented dual-task balance and/or gait was assessed, and articles were published in English. Results: Ten articles met inclusion criteria- three examined dual-task balance and seven dual-task gait. In people with DM with or without peripheral neuropathy, dual-task resulted in larger sway velocities during standing tests. Individuals with DM and peripheral neuropathy had impaired dual-- task gait; specifically, and more consistently, reduced pace and rhythm compared to controls or people with DM without peripheral neuropathy. Conclusion: The findings support a compromise in the cognitive-mobility relationship of people with DM, and especially in those with peripheral neuropathy. Future research should continue to examine the cognitive-mobility relationship in order to understand the increased prevalence of falls in this population.