Depression in individuals with type 2 diabetes mellitus (T2DM) is associated with worse clinical prognosis; however, evidence regarding the relationship between depression and hypoglycaemic risk remains limited and inconclusive.

Our study aimed to evaluate the association between depressive symptoms and hypoglycaemic events.

Depressive symptoms were assessed in participants of the ACCORD-HRQL study at baseline and during follow-up visits at 12, 36 and 48 months using the nine-item Patient Health Questionnaire (PHQ-9). Symptom severity was categorised into three levels: none (0–4 points), mild (5–9 points) or moderate to severe (10–24 points). The primary outcomes included hypoglycaemia requiring any assistance (HAA) and hypoglycaemia requiring medical assistance (HMA).

Over a median follow-up of 4.3 years, 220 individuals developed HAA (incidence rate: 27.0 per 1000 person-years) and 157 individuals experienced HMA (incidence rate: 18.8 per 1000 person-years). Depressive symptoms exhibited dynamic fluctuations during the study period, and participants with depression consistently demonstrated less effective glycaemic control compared to those without depression. However, each one-unit increase in PHQ-9 score was not associated with elevated risks of HAA (hazard ratio, 1.00; 95% CI, 0.97–1.03) or HMA (hazard ratio, 0.98; 95% CI, 0.95–1.02).

Depressive symptoms in individuals with T2DM are dynamic and correlate with suboptimal glycaemic control. However, no significant association was observed between depression severity and increased hypoglycaemic events. These findings highlight the importance of integrated clinical strategies for continuous mental health monitoring and glucose management in T2DM individuals.