Work participation is beneficial for health. Diabetes mellitus is highly prevalent among adults, and although it poses a substantial healthcare cost burden, the true burden might be greater than is currently appreciated through effects on work participation. This Review summarizes the evidence regarding the effect of diabetes mellitus on paid employment. Several studies report increased risks of unemployment, early retirement and productivity loss among those with diabetes mellitus. The presence of diabetes mellitus complications and comorbidities probably further decreases work participation. Studies of workplace interventions demonstrate that work ability can be improved in people with diabetes mellitus. However, most existing research does not consider work characteristics (for example, type of work and working hours) in diabetes mellitus management. Whether diabetes mellitus itself increases occupational injury risk is unclear, with conflicting results reported. Most studies were cross-sectional and limited by use of self-reported diabetes mellitus and outcome measures, without consideration of the type of diabetes mellitus. Guidance on diabetes mellitus and employment has, to date, not been strongly grounded in evidence. Detailed research exploring factors implicated in work outcomes for people with diabetes mellitus, including age, sex, occupation and diabetes mellitus type, is needed to inform policy and support sustainable employment for those with diabetes mellitus.