BACKGROUND: To determine the effect of the health literacy levels of caregivers of individuals with T2DM on caregiving activities and supportive behaviours. METHODS: Cross sectional study. The sample for the study comprised of people who provided care for 442 individuals who were diagnosed with diabetes. The data were collected using the Personal Information Form, HLS-14 and D-CASS. Descriptive statistics, Independent samples t test, One-Way ANOVA and multiple linear regression analysis were used to analyse the data. RESULTS: According to the results of the multiple linear regression analysis, the model was found to be statistically significant, and the variables that were incorporated into the model were able to explain 68.1% of the variance. Among the variables included in the model, HLS-14, educational status, employment status, income status and diabetes-related education were found to affect the care activities and supportive behaviours of caregivers of individuals with diabetes. CONCLUSION: In the research, it was determined that care activities and supportive behaviours were higher in those with higher levels of HL, higher levels of education, those who were not employed, those with higher income levels, and those who received education about diabetes. Nurses should develop training programmes to increase the HL levels of caregivers.