In patients with type 2 diabetes mellitus (T2DM), effective self-management, including medication adherence, physical activity, and lifestyle modification, is crucial to reducing cardiovascular disease risk and improving long-term outcomes [1]. Approximately 25% of individuals with disabilities have T2DM, and people with physical or mental impairments usually face substantial barriers to effective self-management [2]. Prior studies have consistently demonstrated markedly high cardiovascular risk in this population [3-5]. However, the mechanisms underlying this excess risk, especially the role of medication adherence across disability subtypes, remain insufficiently understood. Therefore, we conducted a nationwide cohort study to investigate whether disability subtypes, together with medication adherence, are associated with the risk of long-term cardiovascular events in patients with newly diagnosed T2DM.

This retrospective cohort study was conducted using data from the Korean National Health Insurance Service (KNHIS) database, which provides eligibility records, medical claims, prescription data, and national health screening results. Because of Korea’s biennial national health screening program, the KNHIS database enables longitudinal analyses of associations between health outcomes and changes in lifestyle factors [6]. The study cohort comprised individuals who were newly diagnosed with T2DM between January 1, 2010, and December 31, 2023. We excluded individuals with advanced baseline comorbidities to minimize potential bias. The final analytic cohort comprised 3,652,952 individuals with newly diagnosed T2DM and no prior major cardiovascular or malignant conditions. The exposures were disability including physical disability, visual impairment, hearing impairment, speech impairment, facial disfigurement, epilepsy, and neurodevelopmental or neuropsychiatric disabilities (including intellectual disability, psychiatric disorders, and brain lesion-related conditions) based on national disability registration data. Medication adherence was measured using medication possession ratio (MPR). Poor adherence was defined as MPR <50%. The primary outcome was the incidence of major adverse cardiac and cerebrovascular events (MACCE), defined as a composite of all-cause mortality, myocardial infarction (MI), and stroke. These outcomes were identified using diagnostic codes from inpatient and outpatient claims during the follow-up. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using multivariate Cox proportional hazards models, including age, sex, income, area of residence, smoking status, drink frequency, body mass index, comorbidities, medications, and family history of coronary artery disease. This study was reviewed by the Institutional Review Board (IRB) of Samsung Medical Center (IRB protocol 2024-04-099). Written informed consent by the patients was waived due to a retrospective nature of our study.

Among the study population, 412,173 (11.3%) individuals with T2DM had a disability. Patients with disabilities were older (mean age: 64.5 years vs. 57.8 years), had lower income levels (medical aid: 13.5% vs. 2.7%), and had more comorbidities (mean Charlson comorbidity index: 2.9 vs. 2.4) than did those without disabilities. During median follow-up of 5.9 years (interquartile range, 2.9 to 9.5), the incidence of MACCE was higher in the disability group than in the non-disability group (34.5% vs. 17.4%; adjusted HR, 1.37; 95% CI, 1.36 to 1.38). For the individual MACCE components, patients with disabilities had higher risks of all-cause mortality (19.5% vs. 9.6%; adjusted HR, 1.19; 95% CI, 1.18 to 1.20), MI (2.5% vs. 1.6%; adjusted HR, 1.10; 95% CI, 1.07 to 1.13), and stroke (19.2% vs. 8.5%; adjusted HR, 1.67; 95% CI, 1.65 to 1.68) than did those without disabilities. We further examined the association between disability and cardiovascular outcomes across the disability subtypes. All disability groups, except for facial disfigurement, showed significantly increased MACCE risk compared with that in individuals without disabilities (Fig. 1). The highest risks were observed in patients with neurodevelopmental or neuropsychiatric disabilities (adjusted HR, 3.37; 95% CI, 3.33 to 3.41), followed by those with speech (adjusted HR, 2.98; 95% CI, 2.80 to 3.17) and hearing (adjusted HR, 1.64; 95% CI, 1.62 to 1.66) impairments.

Good adherence to diabetic medication was achieved by 86.6% in the group without disabilities versus 85.8% in the group with disabilities (adjusted odds ratio [OR], 0.92; 95% CI, 0.91 to 0.93). Similarly, adherence to statin was significantly lower in patients with concurrent diabetes and disabilities than in those without disabilities (adjusted OR, 0.83; 95% CI, 0.83 to 0.85). Among patients with concurrent diabetes and disability, good adherence to antidiabetic medications (adjusted HR, 0.79; 95% CI, 0.77 to 0.80) and statin (adjusted HR, 0.74; 95% CI, 0.72 to 0.75) was associated with a substantially low MACCE risk.

In this large nationwide cohort, individuals with disabilities experienced a substantially higher MACCE risk than did those without disabilities. This excess risk was consistent across nearly all disability subtypes. Notably, patients with disabilities were less likely to initiate antidiabetic and statin therapy and demonstrated poorer adherence once treatment was initiated than those without disabilities. Moreover, good adherence to antidiabetic therapy or statins was associated with a lower MACCE risk than that under poor adherence among individuals with T2DM and disabilities.

Consistent with previous reports, the current study showed that individuals with disabilities had significantly worse clinical outcomes than did those without disabilities. Individuals with neurodevelopmental or neuropsychiatric disability and speech impairments exhibited the highest cardiovascular risks. The markedly elevated risk in patients with neurodevelopmental or neuropsychiatric disability may be attributable to a combination of factors, including co-occurring physical impairments despite the primarily cognitive nature of the disability, underlying mental disorders, polypharmacy, and limited access to preventive care [7,8].

Moreover, our study suggests that good medication adherence was associated with a low MACCE risk among patients with disabilities; this has significant clinical implications. Although existing interventions, such as home-based delivery, simplified regimens, and caregiver-assisted management, have been implemented, they have primarily focused on addressing physical access barriers [9]. In addition to previous data, our findings suggest that a more nuanced approach is required. Therefore, future strategies for improved adherence should integrate cognitive support and communication-based intervention, such as personalized counseling, simplified health communication tools, or digital health platforms, designed for cognitive accessibility [10]. Addressing physical and cognitive barriers may be essential for reducing disparities in cardiometabolic outcomes among individuals with disabilities.

This study had several limitations. As a retrospective observational study, our findings are subject to residual confounding and selection bias. We measured medication adherence based on pharmacy refill data rather than actual ingestion. We could not capture data on caregiver support or the quality of physician-patient communication, which may also influence outcomes.

In summary, disability is a significant determinant of adverse cardiovascular outcomes in patients with newly diagnosed T2DM, particularly among those with neurodevelopmental, neuropsychiatric, or communicative impairments. Low adherence to cardiometabolic therapy is a key modifiable factor contributing to this disparity, as improved medication adherence was strongly associated with risk reduction. Therefore, developing disability-inclusive chronic disease management strategies that address barriers to access, promote continuity of care, and support adherence through tailored interventions is imperative.

NOTES

CONFLICTS OF INTEREST

No potential conflict of interest relevant to this article was reported.

Fig. 1.

Hazard ratios for cardiovascular outcomes by disability type among patients with type 2 diabetes mellitus. Forest plots display multivariable-adjusted hazard ratios and 95% confidence intervals for (A) major adverse cardiac and cerebrovascular events (MACCE), (B) all-cause mortality, (C) myocardial infarction, (D) stroke, comparing patients with physical disability, visual impairment, hearing impairment, speech impairment, facial disfigurement, epilepsy, and neurodevelopmental or neuropsychiatric disability, to those without disability. Cox proportional hazards models were adjusted for age, sex, income, residence of area, smoking status, drink frequency, body mass index, comorbidities, medications, and family history of coronary artery disease. The x-axis is presented on a log scale and standardized across all panels to enable visual comparison. ND/NP, neurodevelopmental or neuropsychiatric disability.

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Kim O, Lee M, Hahn W, Kim CH, Kim S, Kang D, Choi KH. Impact of Medication Adherence on Cardiovascular Outcomes in People with Type 2 Diabetes Mellitus and Disabilities. Diabetes Metab J. 2026;50(2):418-421.

DOI: https://doi.org/10.4093/dmj.2025.1261.

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