Introduction
The suicide mortality rate in the world is more than 800000 people a year. For example, in the United States alone, the death toll is nearly 45000 [1]. In a study by the World Health Organization in 21 countries, the prevalence rates of suicidal ideation have been reported to be nearly 2% per year and 9% per lifetime. Additionally, it was shown that among the people with a history of suicidal ideation, the likelihood of a suicide plan is 33%, and that of committing suicide is about 30% [2, 3]. 
Based on the Iranian Legal Medicine Organization’s statistical yearbook (March 2017, March 2018), the comparison of the suspected suicidal death rate (per 100000 people) in different provinces shows that the top-ranking provinces are Ilam with 13.8 deaths and then Boyer Ahamad with 13.7 deaths. According to the latest research of social scientists, the 4-year suicidal rate between March 2015 and March 2019 shows a 60% increase with an annual increase of 15%. Now, the suicide toll has extended beyond the central and western provinces to all over the country. It is noteworthy that the number of suicides during the 3 months of 2022 (March, April, May) compared to the same period of 2021 has increased significantly in quantity and quality [4].
It has been shown that suicide mortality is much higher in men (15 per 100000) than women (8 per 100000), but the prevalence of suicidal ideation is higher among women. The risk factors for suicidal behaviors are female gender, low education, low income, single status, unemployment, parental psychological pathology, childhood problems, and the presence of mental disorders [1, 2, 5].
Based on a previous study, 77% of people who committed suicide had a mental disorder, primarily depression (63%), during their death [6]. Although suicide is considered the most destructive outcome for patients with depression, the particular reasons for suicide attempts in patients with major depressive disorder have not been identified yet [7]. Lately, researchers have focused on identifying biomarkers such as lipid profiles that may be associated with suicidal behavior [8]. Recent studies report the association between diabetes, depressive disorders, and suicidal ideation [9, 10] but only a few studies have been conducted on the association between depression, suicidal behavior, glucose levels, and insulin resistance [11].
Metabolic syndrome refers to a set of conditions: high blood pressure, increased levels of insulin in the blood, excess fat accumulated around the abdomen, and increased levels of blood lipids. According to the researchers, metabolic syndrome is a group of risk factors, including the fatty waist, abdominal obesity, high blood pressure, diabetes, high triglycerides (TGs), and low high-density lipoprotein (HDL) that occur together and increase the risk of heart disease, stroke, and diabetes [12]. Not all experts agree on the definition of metabolic syndrome. Some physicians have other names for these risk factors, such as syndrome X or insulin resistance syndrome [13].
In recent years, the global prevalence of metabolic syndrome has risen in parallel with the rise in diabetes and obesity and has become a major public health concern [14]. The relationship between depression and metabolic syndrome has also been positive and mutual. The prevalence of metabolic syndrome and its components amongst people with severe psychiatric disorders has been reported to be 1.5 to 2 times higher than that in the general population. This high prevalence rate is associated with the unhealthy lifestyle common among these patients, characterized by substance use, smoking, and unhealthy diet [15]. The results of studies on the association between metabolic syndrome and its components with suicidal ideation showed an inconsistency. Some studies found a significant relationship between metabolic syndrome and its components, such as fasting blood sugar (FBS), triglycerides (TG), and high blood pressure with suicidal ideation [16, 17, 18], whereas some studies did not find such relationships [19, 20, 21]. 
Studies on the association between depression, suicidal behavior, and metabolic syndrome are limited [22]. Because of the prevalence of metabolic syndrome and its relationship with psychiatric disorders and the shortage of studies in this field in Iran, we investigated the relationship between depression and suicidal ideation among patients with metabolic syndrome. 
Materials and Method
This study was a descriptive cross-sectional study to determine the prevalence of both depression and suicidal ideation among patients with metabolic syndrome referred to the Endocrinology Department of Afzalipour Hospital, Kerman City, Iran, in 2019. The sample size of 150 is determined based on the previous studies, as the prevalence of suicidal ideation in patients with metabolic syndrome was equal to 20% at the confidence level of 95% [23]. 
In this study, the Beck scale for suicide ideation, Beck Depression Inventory (BDI-II), and demographic information questionnaire were used for data collection. Demographic information included age, sex, marital status, place of residence, educational level, history of metabolic syndrome, the last hemoglobin (Hb)A1C test, complications of metabolic syndrome, the metabolic syndrome treatment, comorbidity, history of mental illness, drug use, body mass index (BMI), blood pressure, high-density lipoprotein (HDL), TG, and waist circumference according to ATP III guidelines.
Physical examination of weight, height, waist circumference, and blood pressure were carried out upon admission of patients wearing light-weighted clothes. 
The waist circumference was measured to the nearest 1.0 cm at the midpoint between the lateral iliac crest and the lowest rib.
Blood pressure was measured twice with a mercury sphygmomanometer while patients relaxed for 15 minutes. Trained nurses carried out all examinations. We executed all the usual quality control methods of a reputable clinical laboratory (teaching hospital, treatment and research, clinical laboratory), including regular testing of standard samples.
After obtaining the ethical code from the Research Council and coordination with Afzalipour Hospital’s security, one of the research assistants was introduced to the participants, and their informed consent was obtained. The purpose and different stages of the research were explained, and the patients were assured of the confidentiality of their information.
The inclusion criteria were metabolic syndrome diagnosis based on ATP III guidelines, hospitalization in the Endocrinology Department of Afzalipour Hospital in Kerman, and willingness to participate in the present study. The exclusion criteria were incompleteness of questionnaire information, more than 30%. Also, the patients with a serious medical or neurological condition other than metabolic syndrome, taking antidepressants or psychotropic drugs in two months prior to the study, or receiving electroconvulsive therapy (ECT) in the six months prior to the study were excluded.
Diagnosis of metabolic syndrome was confirmed according to ATP III guidelines (at least 3 criteria: waist circumference greater than or equal to 102 cm in men and more than or equal to 88 cm in women, triglyceride level more than 150 mg/dL, HDL level less than 40 mg/dL in men and less than 50 mg/dL in women, systolic blood pressure greater than or equal to 130 mm Hg or diastolic blood pressure greater than or equal to 85 mm Hg and fasting blood sugar greater than or equal to 100 mg/dL).
To investigate the severity of depression, the Beck Depression Inventory-2 (BDI-II) was used in this study [24]. BDI-II includes 21 items that assess the patient’s mood over the past 2 weeks. The items in this questionnaire are scored on a 4-point scale from 0 to 3, so the total score may vary between 0 and 63. Beck’s classification of the severity of depression on this scale ranges from asymptomatic (0–9), mild depression (10–18), moderate depression (19–29), and severe depression (30–63) [25]. In the Iranian population, the BDI-II has shown high internal consistency (α=0.92) and good reliability [26, 27].
The second questionnaire was the Beck Scale for Suicidal Ideation (BSSI). This questionnaire is a 19-item self-assessment tool designed to evaluate attitudes, ideation, and planning for suicide. The first 5 questions have been prepared for screening. Therefore, if patients give a 0 score to the first 5 questions, they have no suicidal ideation. A score of 1 to 5 indicates suicidal ideation, 6 to 19 indicates a readiness to commit suicide, and a score of 20 to 38 indicates an intention to commit suicide. This questionnaire is a valid and reliable tool for measuring suicidal ideation [27]. High credibility was also found for BSSI among the Iranian population (the Cronbach α=0.95) [28].
Furthermore, drug users were identified after a full explanation was given about drugs and their frequent usage. The patients who self-reported the illegal and street usage of non-prescribed drugs on a regular basis for more than 3 months (Those who were under addiction treatment were not in this group) were enlisted as drug users. 
 The research assistant completed the questionnaire through an interview with sufficient time in accordance with the patient’s information, and all participants were assured of their information confidentiality. This research was approved with the ethical code IR.KMU.AH.REC.1398.129. The questionnaires were anonymous to further protect participants disclosed information and secrets.
After extracting and recording the data, they were analyzed by SPSS version 20, and a P value less than 0.05 was considered statistically significant. To describe qualitative variables, frequency distribution and percentage indices were used. Also, to describe quantitative variables, mean and standard deviation were used. Analysis of variance, the t test, Pearson test, Spearman test, and multiple regression were performed for statistical analyses.
Results
Data analysis showed that 52.8% of participants were male, 36.6% had a bachelor’s degree, 87.3% were married, and 77.4% lived in the city. Also, 24% had a history of mental illness, 49.3% had a history of physical illness, and 23.4% had a history of drug use. Other demographic information of the participants is presented in Table 1.


Furthermore, the mean±SD age of the participants was 41.4±15.3 years, and the disease’s duration was 5.1± 1.67 years. Moreover, their mean±SD BMI was 26.6±2.4 kg/m2, and of HDL, TGS, FBS, and HbA1C were 39.4±5.1 mg/dl, 168.9±58.4 mg/dl, 121.1±9.8 mg/dl, and 6.8±1.3, respectively. Further descriptive results for the participants are given in Table 2.


The mean±SD depression score of the participants was 19.1±3.3 (out of 63), and 38% of the participants had mild, 16% moderate, and 5.4% severe depression. The mean ± SD suicidal ideation score of the participants was 13.4±5.3. According to the results, 42% of participants did not have suicidal ideation, 50% had suicidal ideation, and 8% were ready to commit suicide.
The results of the present study showed significant relationships between the suicide scores of the participants and gender (P=0.03), marital status (P=0.01), level of education (P=0.02), history of mental illness (P=0.03), and history of physical illness (P=0.04). Accordingly, suicidal ideation was higher in women, singles, diploma holders, and those with a history of physical or mental diseases. However, there was no statistically significant relationship between suicide score and participants’ place of residence (P=0.08) and drug abuse (P=0.07).
Additionally, the results of the present study showed positive and significant correlations between the score of suicidal ideation and the mean age (r=0.73, P=0.03), duration of illness (r=0.72, P=0.04), body mass index (r=0.84, P=0.01), mean HbA1C level (r=0.87, P=0.03), FBS (r=0.71, P=0.01) and depression score (r=0.68, P=0.03). Also, a significant negative correlation was observed between the score of suicidal ideation and HDL level (r= -0.79, P=0.02), while there was no significant correlation between suicide score and other quantitative variables.
Discussion
This research was a descriptive-analytical (cross-sectional) study performed on a sample of 150 eligible participants to determine the rate of depression and suicidal ideation in patients with metabolic syndrome referred to the Endocrinology Department of Afzalipour Hospital, Kerman City, Iran, in 2019. Suicidal ideation was significantly higher in women, singles, high school diploma holders, and those with a history of mental and physical illness. There was also a significant positive correlation between suicidal score and mean age, duration of illness, body mass index, HbA1C level, FBS, and depression score. Also, there was a significant negative correlation between suicide score and HDL level. Finally, there was no significant relationship between suicide score and living in the city and drug use.
A high prevalence of suicidal ideation was observed in these patients; 50% of the samples had suicidal ideation, and 8% were ready to commit suicide. In 2019, a population-based research study in Brazil found a 40.8% suicide risk among metabolic syndrome patients [30]. This finding is consistent with our study. Furthermore, Fagiolini et al. showed a significantly higher prevalence of lifetime suicide attempts (53%) among metabolic syndrome patients compared to other patients [31], which is consistent with this study. Moreover, a Finnish research study on the relationship between suicidal ideation and impaired glucose metabolism in patients with depressive disorder showed a suicide ideation prevalence rate of 49% and a higher cholesterol level among these patients [32]. Also, in our research, 59.4% of the samples had depression, which could explain the high rate of suicidal ideation among patients with metabolic syndrome. Therefore, suicide prediction strategies focusing on psychological and medical risk factors may provide new insights into the design of screening and prevention programs for suicidal patients [32].
The results of the present study showed that FBS and HDL levels in patients with metabolic syndrome have a significant correlation with the suicidal ideation score (positive correlation with FBS and negative correlation with HDL). Similarly, the relationship between higher HbA1C levels and suicidal ideation was consistent with the several research studies in this field [8, 9, 16, 17, 18, 31] and indicated the strong role of this multifactorial disorder in the formation and strengthening of suicidal ideation in people with this complication.
On the other hand, a comparative study by Maslov et al. on patients with post-traumatic stress disorder and schizophrenia did not find any correlation between suicide attempts and metabolic syndrome in schizophrenic patients; however, there was a difference in post-traumatic stress disorder patients [19]. The lack of a relationship between metabolic syndrome and suicide in schizophrenic patients is the close relationship between schizophrenia and suicide due to personal distress and social work performance impairment, and reduced life expectancy in general in these patients [33].
In a study conducted by Bidaki et al. in Iran (city of Rafsanjan), the reason for the low prevalence of suicidal ideation in diabetic patients was attributed to cultural and religious issues, and these patients may hide their suicide due to public opinion or may even have a serious suicide attempt but would not reveal it [20].
The biological mechanisms for the association of metabolic syndrome and its components with suicidal ideation are not yet fully understood. However, it is possible that some conditions created during the metabolic syndrome, such as insulin resistance, are involved in this process [17]. A hypothesis has also been proposed regarding the relationship between cholesterol and the serotonergic system: a decrease in serum cholesterol level may be associated with changes in the viscosity and function of serotonin receptors and transporters, as well as a decrease in serotonin precursors [33]. The association of the serotonergic system with suicide and impulsive and aggressive behavior is well known because several studies have found lower concentrations of 5-hydroxy indole acetic acid (5-HIAA) in cerebrospinal fluid of those who committed and attempted suicide [35].
This study showed a positive and significant correlation between depression and suicidal ideation of participants. In our study, the prevalence rates of mild, moderate, and severe depression were 38%, 16%, and 5.4%, respectively, and 59.4% in total, which is significantly higher than the prevalence rate among the population of Iran reported to be 25% [36]. This result could indicate the effect of metabolic syndrome on depression. 
 The association between depression and metabolic syndrome is positive and mutual [15]. Also, recent studies have reported associations between diabetes, depressive disorders, and suicidal ideation [9, 10], all of which are consistent with this study. Depression is a factor that, apart from psychological status, has a negative impact on physical condition, job, and social performance leading to dysfunction in large part of the depressed person’s life. A wide range of negative factors could reinforce the attitude to end the negative life and lead the depressed person to suicide [37].
The body mass index may be an important risk factor for suicidal behavior, consistent with this study and a systematic review [38]. With regard to the psychosocial stigma and health-related complications of obesity, a positive relationship between obesity and depression has been shown [39]. The hyperactivity of the hypothalamic-pituitary-adrenal axis has been reported in 20% to 80% of depressed individuals. This hyperactivity has been suggested as an important mechanism that explains both the pathophysiology of depression and its association with medical conditions such as diabetes and obesity [40].
This study showed a significant relationship between patients’ gender and suicidal ideation. Suicidal ideation is higher in women, which is consistent with the results of other studies in this area [1, 2, 5, 37]. The reason can be attributed to the different stresses occurring for women at different stages of life, disorders caused by certain events such as pregnancy, childbirth, and its effects, hormonal changes, social roles, cultural differences, and behavioral expectations from women (compared to men) [41].
A positive and significant correlation was found between age and suicidal ideation in this study, which is consistent with other relevant studies [42, 43]. This finding reflects the sedentary lifestyle and inadequate diet of the elderly [30]. However, in some studies in this field, no significant relationship was observed between age and suicidal ideation [32]. The reason could be explained in the statistical sampling of those research studies. The discrepancy could be that all participants of this research were patients admitted to the educational treatment center, but in the mentioned studies, suicidal ideation was examined in ordinary people across the community. Conceivably due to the older age of the participants, the results of the study can not be generalized to young people or should be done with caution [44]. In the present study, the highest score of suicidal ideation belonged to the people with a diploma and lower. Education has been identified as a protective factor from metabolic syndrome [43].
In this study, a statistically significant relationship was observed between suicidal ideation and duration of illness and history of physical and psychiatric illness, which is consistent with other studies in this field [30, 42, 43, 45]. Chronic physical illnesses increase the risk of suicide. Physical health is directly related to mental health, and physical illness may create psychiatric symptoms. Alternatively, psychiatric symptoms like depression may reduce the ability of patients to communicate their physical needs [46].
Conclusion
A correlation was observed between the score of suicidal ideation and mean age, duration of illness, body mass index, FBS, and HDL. Awareness of these factors can help identify high-risk people. Therefore, it is recommended that particular consideration be given to the various dimensions of psychological and psychiatric issues related to this group of people, and the patients with metabolic syndrome are evaluated for depression and the possibility of suicidal ideation and self-harm during hospitalization.
One of the limitations of the present study was the few treatment centers. Moreover, it was only performed on hospitalized individuals. Due to the prevalence of diabetes and overweight in the community, it is suggested that a more comprehensive sample be examined. To study casual relationships, a longitudinal observation is recommended.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of the Kerman university of medical sciences (Code: IR.KMU.AH.REC.1398.129)

Funding
This essay is taken from the thesis of medical student Sajde Zamanizadeh, Faculty of Medicine, Kerman University of Medical Sciences.

Authors' contributions
Conceptualization and Supervision: Parisa Divsalar; Methodology: Mohammad Hossein Gozashti;  data collection and analysis sajedeh zamani zadeh;Investigation, writing, original draft, review and editing: all authors.

Conflict of interest
The authors declared no conflict of interest.

Acknowledgments
The authors appreciate all patients with metabolic syndrome who participated in this study, as well as the officials and staff of Afzalipour Hospital in Kerman, especially the staff Department of Endocrinology.


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