Intellectual developmental disability and risk of developing depression in type 2 diabetes

Type 2 diabetes (T2D) places substantial physiological and psychological demands on patients and is independently linked to an elevated risk of depression. Intellectual developmental disability (IDD) is likewise associated with metabolic disorders and a high prevalence of mood disturbances, yet communication barriers often delay diagnosis. Whether coexistence of IDD further amplifies the likelihood of new-onset depression in people with T2D remains unclear. We aimed to investigate the association between IDD and incident depression among Korean adults with T2D.

We analyzed 1,819,869 adults (≥ 20 years) with T2D who underwent the 2015-2016 Korea National Health Screening Program. Participants were classified as either IDD (n = 3665) or non-IDD groups. The primary outcome was new-onset depression identified up to 31 December 2022 following the health-screening date. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident depression.

Participants with IDD were younger (mean age: 49.2 vs. 58.0 years) and had a lower proportion of men (55.9% vs. 61.8%) than those without IDD. Over a median follow-up of 5.8 years, 14.8% developed depression, with an elevated risk in the IDD group (HR 1.65, 95% CI: 1.53-1.77). This association was consistent across IDD severity and was especially marked in individuals under 65 and with T2D duration under five years.

Coexisting IDD and T2D are linked to higher depression risk. Our finding underscores the need for tailored interventions, improved caregiver awareness, and enhanced screening to address mental health disparities.