Aim Self-management of diabetes is influenced by a range of factors including the ability to access, understand, appraise, and use of health information in everyday life, which can collectively be called health literacy. We investigated associations between nine domains of health literacy and HbA1c level in people with type 1 diabetes. Methods A cross-sectional study was conducted with 1399 people with type 1 diabetes attending a Danish specialist diabetes clinic. Health literacy was assessed using the nine-domain Health Literacy Questionnaire. The association between health literacy and HbA1c was analyzed using linear regression with adjustment for age, sex, educational attainment and diabetes duration. Results Of the 1399 participants, 50% were women, mean age was 54 years, and mean HbA1c was 61 mmol/mol (7.8%). Higher health literacy scores were associated with lower HbA1c levels across eight of nine health literacy domains. This association remained significant after adjusting for educational attainment. Among the domains, Actively managing my health' had the strongest impact on HbA1c. This was in turn predicted by Appraising health information', Having sufficient information to manage health', and Social support for health'. Conclusions Higher health literacy levels are associated with lower HbA1c regardless of educational background. This study highlights the importance of healthcare provision to respond to the health literacy levels of people with diabetes and to the possible need to provide program designed to enhance health literacy.