AimTo examine whether diabetes-specific emotional distress was related to follow-up glycaemic control in adults with Type 1 diabetes mellitus.MethodsAdults with Type 1 diabetes mellitus completed the Diabetes Distress Scale and reported sociodemographic information when attending a clinical consultation at a university endocrinology unit. Blood samples to determine baseline HbA1c were taken during consultations. All respondents’ HbA1c measurements registered from January 2009 to December 2011 were collected from medical records. The relationship between baseline diabetes-specific emotional distress and HbA1c was examined with linear mixed-effects models in 175 patients with complete data.ResultsAfter controlling for confounders, baseline diabetes-specific emotional distress and glycaemic control were significantly associated (fixed-effect coefficient 0.40, P < 0.001) and the regimen-related distress subscale had the strongest association with glycaemic control (fixed-effect coefficient 0.47, P < 0.001). The two-item measure of diabetes-specific distress had a weaker but still significant association with glycaemic control (fixed-effect coefficient 0.31, P < 0.001). None of these relationships was significant after adjusting for the baseline HbA1c.ConclusionsPeople with elevated baseline diabetes-specific emotional distress are at risk of prolonged suboptimum glycaemic control; therefore, elevated diabetes-specific emotional distress, especially regimen-related distress, might be an important marker for prolonged suboptimum glycaemic control, and might indicate a need for special attention regarding patient self-management.What’s new? In adults with Type 1 diabetes, elevated baseline diabetes-specific emotional distress is associated with worse glycaemic control over a 1–3-year period and regimen-related distress had the strongest association with subsequent glycaemic control. Baseline diabetes-specific emotional distress is associated with the stable component of glycaemic control and does not account for within-individual change in glycaemic control over 1–3 years. Elevated diabetes-specific emotional distress may be an important marker for risk of prolonged suboptimum glycaemic control.