Sex Disparity in Suicide Mortality among Patients with Type 2 Diabetes: A Nationwide Population-Based Cohort Study

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Endocrinol Metab. 2026;41(3):405-414

Publication date (electronic) : 2026 March 19

doi : https://doi.org/10.3803/EnM.2025.2669

Chaiho Jeong¹, Bongseong Kim², Dae Jong Oh³, Tae-Seo Sohn¹, Kyungdo Han^,4, Hyuk-Sang Kwon^,1

¹Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea

²Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea

³Workplace Mental Health Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea

⁴Department of Statistics and Actuarial Science, Soongsil University, Seoul, Korea

Corresponding authors: Hyuk-Sang Kwon. Division of Endocrinology and Metabolism, Department of Internal Medicine, Yeouido St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 10 63-ro, Yeongdeungpo-gu, Seoul 07345, Korea Tel: +82-2-3779-1261, Fax: +82-2-786-1471, E-mail: drkwon@catholic.ac.kr

Kyungdo Han. Department of Statistics and Actuarial Science, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul 06978, Korea Tel: +82-2-820-7025, Fax: +82-2-823-1746, E-mail: hkd917@naver.com

Received 2025 September 16; Revised 2025 November 20; Accepted 2025 November 24.

Abstract

INTRODUCTION

Suicide constitutes a major public health issue globally and is especially pronounced in Korea, where it ranks as the fifth leading cause of death [1,2]. Identification and intervention among high-risk populations are essential for effective suicide prevention, with patients with diabetes recognized as one such at-risk group [3-5]. Importantly, diabetes is also the seventh leading cause of death in Korea [2], underscoring the urgency of addressing suicide in individuals affected by diabetes as a significant overlapping public health concern. Individuals with diabetes frequently face difficulties in maintaining necessary lifestyle modifications and adhering to prescribed treatment plans, which can elevate psychological burden and increase suicide risk. Additionally, it has been observed that patients with diabetes may attempt suicide through the use of prescribed medications, including insulin or oral hypoglycemic agents (OHAs) [6-8]. Enhanced access to pharmacological agents with lethal potential may serve as a unique structural risk factor for suicide within this group, distinguishing them from the general population [9]. Despite the criticality of this problem, research on suicide mortality in individuals with diabetes remains limited. As a result, the epidemiological patterns and contributing risk factors among this population are yet to be fully clarified.

Effective prevention strategies require a comprehensive assessment of suicide prevalence among individuals with diabetes and the identification of associated risk factors. Documented sex differences exist in both suicide mortality and diabetes epidemiology. Overall, male individuals exhibit a higher suicide mortality compared to females [10,11]. However, it is unclear whether such sex differences in suicide mortality are also present among patients with diabetes. Epidemiological data suggest that men are more likely to be affected by type 2 diabetes mellitus (T2DM) than women [12,13]. Conversely, women experience a marked increase in T2DM risk after menopause and are often diagnosed at an older age and with higher adiposity than men [14,15]. Furthermore, women with T2DM face a greater relative risk for cardiovascular disease compared to men and demonstrate more than double the prevalence of depression [14,16,17]. These distinctions support the possibility that sex may modify the association between diabetes and suicide mortality. Accordingly, the present nationwide cohort study seeks to determine the influence of sex on suicide mortality in patients with T2DM and to examine whether sex alters the associations between established risk factors and suicide risk.

METHODS

RESULTS

Baseline characteristics

Table 1 summarizes the baseline characteristics of the study population. The mean age for male participants was 57.67±11.84 years, while female participants had a mean age of 62.68±11.66 years. Newly diagnosed T2DM was more frequent in men (33.2%) compared to women (22.2%), whereas a longer diabetes duration (≥10 years) was somewhat more common among women (27.6%) than men (22.7%). The frequency of insulin use was also higher in women (9.6%) than in men (8.1%). Men accounted for the vast majority of current smokers (94.0%) and ex-smokers (96.8%), while among never-smokers, 68.5% were women. Heavy alcohol consumption (≥30 g/day) occurred in 14.5% of men, but only 0.8% of women. The prevalence of depression in women (11.8%) was also more than twice that in men (5.8%).

Table 1.

Baseline Characteristics of Study Participants

Risk of suicide mortality according to sex

Over a mean follow-up period of 5.8±1.0 years (median 6.0 years), there were 5,584 (0.22%) deaths by suicide, including 4,536 (0.30%) men and 1,048 (0.10%) women. Table 2 shows the risk of suicide death by sex. Male participants had a significantly higher risk of suicide mortality compared to females in both crude (HR, 2.90; 95% CI, 2.71 to 3.10) and fully adjusted models (HR, 2.88; 95% CI, 2.66 to 3.12). Fig. 1 displays the Kaplan-Meier curves depicting the cumulative incidence of suicide mortality by sex, illustrating a consistently lower cumulative risk in females (log-rank test, P<0.01).

Table 2.

Risk of Suicide Death according to Sex

Fig. 1.

Kaplan-Meier curves illustrating the cumulative incidence of suicide mortality throughout the follow-up period by sex. The figure is limited to 6 years to maintain statistical stability, as the number of individuals at risk decreased substantially beyond this point.

Sex-specific risk of suicide mortality across age group

Fig. 2 displays the distribution of suicide incidence rates by age group for both males and females. While the incidence of suicide among females demonstrated relative stability across different age groups, suicide rates in males increased significantly with age. As a result, the disparity between sexes in suicide mortality became much more pronounced in older age groups. The narrowest gap between sexes was noted in the 30–39 age group (HR, 1.53; 95% CI, 0.98 to 2.40), whereas the widest disparity occurred in those aged ≥80 years (HR, 3.60; 95% CI, 2.88 to 4.51). Detailed age-specific suicide mortality rates, using both 10- and 5-year intervals, can be found in Supplemental Tables S2, S3.

Fig. 2.

Age-specific suicide incidence rates according to sex. ^aPer 1,000 person-years.

Sex disparities in the risk of suicide death according to subgroups

The comparative risk of suicide death for males and females was assessed within subgroups defined by smoking status, alcohol consumption, depression history, diabetes duration, insulin treatment, and use of three or more OHA (Fig. 3). Notable interactions were identified for smoking status, alcohol usage, and history of depression (all P value for interaction <0.05). The disparity in suicide mortality between sexes was highest among non-smokers, with an HR of 3.51 (95% CI, 3.22 to 3.83), compared to 1.95 (95% CI, 1.32 to 2.87) in ex-smokers and 1.73 (95% CI, 1.40 to 2.14) in current smokers. A comparable trend appeared in relation to alcohol consumption: HR was 3.04 (95% CI, 2.79 to 3.31) in non-drinkers, 2.32 (95% CI, 1.92 to 2.80) in mild drinkers, and 1.36 (95% CI, 0.85 to 2.18) in heavy drinkers. Depression history also showed a significant interaction, with an HR of 3.03 (95% CI, 2.76 to 3.32) among those without depression and 2.57 (95% CI, 2.26 to 2.94) among those with a prior depression diagnosis. No meaningful interactions were detected regarding diabetes duration, use of three or more OHA, or insulin therapy. Further subgroup analysis based on income status, presence of obesity, and engagement in regular physical activity did not reveal significant interaction effects between these variables and sex concerning suicide mortality.

Fig. 3.

Forest plot illustrating hazard ratios for suicide mortality among males versus females with type 2 diabetes mellitus, with analyses stratified by subgroups. OHA, oral hypoglycemic agent. ^aP value for interaction.

DISCUSSION

In this nationwide cohort study of more than 2.5 million individuals with T2DM, we identified a marked sex difference in suicide mortality. Over a median follow-up of 6.0 years, men had an almost three-fold greater risk of suicide death in comparison to women. This higher risk was consistent across a range of subgroups, such as those defined by insulin use, diabetes duration, and number of OHA used.

One notable finding of our study is that the sex disparity in suicide mortality among patients with T2DM was more apparent than what is seen in the general Korean population. In recent years, the male-to-female suicide mortality ratio in the general population has stayed around 2.3 [2]. However, in our T2DM cohort, this ratio increased to 2.9, indicating that diabetes may heighten the suicide risk in men to a greater degree than in women. Men in our cohort generally had higher income status, lower rates of insulin use, engaged more frequently in physical activity, and exhibited a lower prevalence of depression—these are typically considered protective factors against suicide [19-22]. Despite these factors, our findings, both before and after socioeconomic adjustment, consistently demonstrate that men with T2DM may face a heightened vulnerability to suicide. In the general population, the higher suicide mortality among men is often attributed to the use of more lethal means, higher levels of substance abuse, reduced healthcare access, and stronger suicidal intent [23-25]. These issues may be even more prevalent in men with T2DM because they tend to be less proactive in seeking medical care [26]. This lack of healthcare engagement can compromise diabetes management, thereby increasing psychological distress and the likelihood of suicide.

Notably, our study revealed that the impact of T2DM on suicide mortality differed across age groups. The sex disparity in suicide mortality became more pronounced with advancing age, mirroring broader epidemiologic trends in Korea, where suicide rates are known to be especially elevated among the elderly. According to 2023 national statistics, the suicide mortality rate for men aged 80 years or older was 3.9 times that for women [2]. A corresponding trend was identified in our T2DM cohort, where the male-to-female suicide mortality ratio reached 3.6 within this age bracket. This substantial disparity may partly result from increased social isolation and diminished social support following retirement among men [27]. Furthermore, Korea has the highest rate of elderly poverty among Organisation for Economic Co-operation and Development countries, and prior studies have found that low economic status is strongly associated with suicidal ideation in elderly men, whereas this association is not observed in women [28,29].

However, a closer examination of age-specific patterns compared to national data reveals that the relative sex disparity associated with T2DM is most pronounced during midlife. In the general Korean population, the male-to-female ratio for suicide mortality increases gradually with age, rising from 2.2 among individuals in their 40s to 3.0 among those in their 60s [2]. In our longitudinal cohort of patients with T2DM, however, the disparity was even greater, with the incidence rate ratio rising from 2.6 to 3.7 across these same age groups. These findings indicate that the interaction of sex, age, and T2DM may heighten suicide vulnerability during midlife, a time often marked by peak occupational, familial, and societal responsibilities. Middle-aged men with T2DM may experience greater physical limitations and diabetes-related complications, which can contribute to psychological distress [30,31]. In sociocultural settings characterized by strong traditional gender roles, men often face increased pressure to meet financial and caregiving obligations [32,33]. In addition, the cumulative effects of chronic disease and ongoing treatment demands may further elevate mental health risks. Notably, men are less likely to seek or engage in mental health treatment [26,34,35]. Consequently, psychological symptoms may go undetected and untreated, thereby increasing the risk of suicidal behavior in this age group. Overall, these findings suggest that T2DM may serve to intensify sex disparities in suicide risk during middle age. This underscores a need for targeted screening and gender-sensitive mental health interventions for this particularly high-risk group.

In addition to age, lifestyle-related risk factors appeared to contribute to the sex-specific patterns of suicide mortality in T2DM. Contrary to the common societal perception that men are more vulnerable due to higher rates of alcohol and substance use, our findings revealed that the sex disparity in suicide mortality was significantly reduced among smokers and heavy drinkers. The disparity was more than halved in these groups compared to non-smokers or non-drinkers. These results indicate that smoking and alcohol consumption may have had a disproportionately stronger effect on suicide risk among women with T2DM than among men. Several mechanisms may underlie this pattern. First, smoking and alcohol consumption are often used as maladaptive coping strategies for stress and emotional distress, and previous studies suggest that women experience a stronger psychological response to these behaviors than men [36,37]. For instance, a study based on the Korean Community Health Survey reported that women who consumed alcohol ≥4 times per week had a 1.91-fold higher risk of suicide attempts compared to non-drinkers, whereas men did not show a significant increase in suicide attempts with higher drinking frequency [37]. Similarly, female smokers have been shown to be more susceptible than males to depressive symptoms and suicidal ideation [38,39]. Second, cultural norms in Korea traditionally stigmatize female smoking and heavy drinking, resulting in possible underreporting and underdiagnosis of substance- related psychological distress among women [40]. As a result, women with T2DM who engage in these behaviors may represent a subgroup with more severe underlying affective symptoms and unrecognized mental health needs, which may contribute to an elevated suicide risk that narrows the overall sex gap. These findings raise the hypothesis that lifestyle factors such as smoking and alcohol use may exert a more detrimental impact on suicide risk in women than in men, even among individuals with T2DM [38,41].

To our knowledge, this is the first large-scale, population-based study to examine sex disparities in suicide mortality among patients with T2DM. Investigating this association in a high-risk population yields important public health implications. Utilizing data from over 2.5 million patients greatly increased the robustness of our findings. Our results underscore the need for integrating mental health evaluation into routine diabetes care, particularly for middle-aged and older men with T2DM who exhibit higher suicide risk. Regular use of screening tools for depression or suicidal ideation during diabetes follow-up visits could facilitate earlier identification of psychological distress. Public health policies should also consider tailored interventions addressing gender-specific risk factors, including reduced healthcare utilization among men and greater psychosocial impact of lifestyle factors such as alcohol use among women. However, certain limitations of this study should be considered. First, although we compared incidence-based suicide mortality rates from our longitudinal cohort with cross-sectional suicide statistics from the general population, there are inherent methodological differences between these approaches. National statistics typically use annualized crude mortality rates, while our study applied person-time incidence rates based on a cohort design. Although such comparisons offer valuable context, differences in study design and statistical measurement methods restrict the direct comparability of results. Thus, the discrepancies observed between our findings and national statistics should be interpreted carefully. Second, this study assumed the stability of clinical characteristics during the follow-up period. Since these variables were measured only once at a single health examination, it is uncertain whether participants’ clinical status remained consistent throughout the study. Moreover, our cohort included only individuals who participated in the NHIS health screening program. Those who do not attend health examinations, particularly individuals living in extreme poverty or with unstable living conditions, may be underrepresented despite their higher risk of suicide. As a result, this study may not fully represent the most socioeconomically disadvantaged groups. Third, although we accounted for multiple potential confounders such as fasting glucose level, diabetes duration, and insulin use, residual confounding may still exist. Specifically, unmeasured factors, including socioeconomic factors such as occupational status or wealth, could have affected the observed associations. Fourth, the NHIS database identifies suicide deaths using ICD-10 codes but does not provide detailed information on the specific methods or substances involved. Therefore, we were unable to determine whether insulin or OHAs were used as suicide methods. This limitation precludes a more detailed investigation of T2DM-specific suicide mechanisms and should be addressed in future research. Lastly, this study was conducted in a Korean population, which has one of the highest suicide rates worldwide [42]. The generalizability of these findings to populations with different cultural or demographic contexts may therefore be limited.

In conclusion, this large-scale, population-based study identified prominent sex disparities in suicide mortality among patients with T2DM. Male patients faced a significantly greater risk of suicide death in comparison to female patients, with the relative gap most notable during midlife relative to the general population. The sex disparity was diminished among current smokers and heavy alcohol consumers. These results highlight the importance of sex-specific suicide prevention efforts for this high-risk population.

Supplementary Material

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