BACKGROUND From a diabetes management perspective, informal care has proven at least as important as care from health professionals when targeting poorly controlled diabetes. The objective of this study was to identify determinants associated with unmet needs for informal support among people with type-2 diabetes in rural communities of Vietnam. METHODS A cross-sectional survey was conducted from December 2018 to February 2019 in a rural area of northern Vietnam. From 2 districts in Thai Binh Province, Vietnam, 806 people with type-2 diabetes participated in a survey designed to assess who were their most important informal caregivers (ICGs) and to measure the association between demographic and socio-economic predictors and unmet needs of informal support of relevance for diabetes self-care using bivariate and multivariate analyses. RESULTS The spouse was reported as the most important ICG (62.9%) followed by a daughter or son (28.4%). 32.0% of the people with type-2 diabetes reported at least one type of unmet need for informal support. The most commonly reported unmet needs of informal care were: transport to health facilities and company when seeking formal care (20.5%), financial support related to costs of diabetes self-management (18.5%), and reminders to engage in physical exercise (14.5%). People living alone reported the highest odds ratio (OR) for unmet need of informal care (OR=4.41; CI95%: 2.19-8.88), followed by those being poor as compared to being wealthy (OR=3.79; CI95%: 1.25-11.52) and those being unemployed as compared to being retired (OR=2.85; CI95%: 1.61-5.05). CONCLUSIONS Almost one-third of people with type-2 diabetes reported at least one type of unmet need for informal care. These findings provide a basis for development of new modalities for strengthening support provided by ICGs in rural communities in Vietnam and in other low- and middle-income countries.