Diabetes mellitus represents a major global public health challenge, with rapidly increasing prevalence and substantial morbidity. According to the International Diabetes Federation, over 537 million adults were living with diabetes worldwide in 2021, with projections indicating a continued upward trajectory by 2030 [1]. Chronic diabetes is associated not only with microvascular and macrovascular complications but also with significant psychological distress. Depression is one of the most common psychiatric comorbidities in individuals with diabetes, occurring nearly twice as often as in the general population [2]. The bidirectional relationship between diabetes and depression is well established, whereby depression contributes to poor self-care behaviors, medication non-adherence, unhealthy lifestyle choices, and worsening glycemic control, while chronic hyperglycemia and diabetes-related complications increase vulnerability to depressive disorders [3]. In low- and middle-income countries such as India, the coexistence of diabetes and depression poses unique challenges due to limited mental health resources, stigma, and fragmented healthcare delivery systems [4]. Studies conducted in Indian settings have demonstrated wide variability in reported prevalence of depression among diabetic patients, ranging from 25% to over 45%, reflecting differences in study design, screening tools, and population characteristics [5]. Recent evidence emphasizes the importance of integrated care models addressing both physical and mental health aspects of chronic diseases. Research has highlighted the broader burden of mental health disorders in clinical populations and their impact on quality of life and healthcare outcomes [6–8]. Studies have similarly underscored the importance of holistic patient management and psychosocial dimensions of chronic disease care [9–11]. Despite growing awareness, depression remains underdiagnosed and undertreated among patients with diabetes. This study was therefore undertaken to evaluate the prevalence of depression in patients suffering from chronic diabetes and to identify key clinical and sociodemographic correlates, with the aim of informing integrated care strategies.

Study Design and Setting A hospital-based cross-sectional observational study was conducted over a 12-month period in the Department of Medicine of a tertiary care teaching hospital in India. Study Population Adult patients aged ≥18 years with a confirmed diagnosis of type 2 diabetes mellitus for at least 5 years were consecutively recruited from outpatient and inpatient services. Inclusion Criteria • Diagnosed type 2 diabetes mellitus ≥5 years • Willingness to participate and provide informed consent Exclusion Criteria • Known psychiatric illness diagnosed prior to diabetes • Current use of antidepressant or antipsychotic medications • Severe cognitive impairment or acute medical illness Sample Size Based on an anticipated depression prevalence of 35%, a confidence level of 95%, and margin of error of 6%, the minimum required sample size was calculated as 230. A total of 240 patients were included. Data Collection A structured proforma was used to record: • Sociodemographic variables (age, sex, education, occupation) • Clinical variables (duration of diabetes, treatment modality, HbA1c) • Presence of diabetes-related complications Assessment of Depression Depression was assessed using the Patient Health Questionnaire-9 (PHQ-9), a validated screening tool widely used in medical settings. Scores were categorized as: • 0–4: No depression • 5–9: Mild depression • 10–14: Moderate depression • ≥15: Moderately severe to severe depression Ethical Considerations The study was approved by the Institutional Ethics Committee. Written informed consent was obtained from all participant. Statistical Analysis Data were analyzed using SPSS version 23. Descriptive statistics were expressed as mean ± SD or percentages. Associations were tested using chi-square and independent t-tests. A p-value <0.05 was considered statistically significant.

The study included a total of 240 patients with chronic diabetes mellitus, whose sociodemographic and clinical characteristics are summarized in Table 1 and Table 2. Sociodemographic Profile The mean age of the study population was 56.4 ± 9.8 years, with the majority of participants belonging to the middle-aged and older adult groups. Male participants constituted 55.0%, while 45.0% were female. A higher proportion of patients resided in urban areas (60.8%) compared to rural regions (39.2%). These findings indicate that chronic diabetes in the present cohort predominantly affected middle-aged adults, with a slight male predominance and greater urban representation (Table 1). Clinical Characteristics of Diabetes The mean duration of diabetes among participants was 9.6 ± 3.8 years, reflecting a largely chronic disease population. More than half of the patients (59.2%) had poor glycemic control, defined as HbA1c ≥8%. Insulin therapy was required in 40.8% of cases, while 52.5% of patients had at least one documented diabetes-related complication, including retinopathy, neuropathy, or nephropathy. These findings highlight a substantial burden of advanced disease and metabolic dysregulation within the study population (Table 2). Prevalence and Severity of Depression Assessment using the PHQ-9 scale revealed that 38.3% of patients exhibited depressive symptoms (PHQ-9 score ≥5). Mild depression was observed in 19.2%, moderate depression in 12.5%, and severe depression in 6.6% of participants. Conversely, 61.7% of patients did not demonstrate clinically significant depressive symptoms. The distribution of depression severity underscores that a considerable proportion of patients experienced moderate-to-severe depression, warranting clinical attention (Table 3). Association Between Depression and Clinical Variables Depression was significantly associated with several clinical parameters related to diabetes severity. Patients with poor glycemic control (HbA1c ≥8%) demonstrated a markedly higher prevalence of depression (48.6%) compared to those with better glycemic control, and this association was statistically significant (p = 0.002). Similarly, patients with a diabetes duration of ≥10 years showed a significantly higher prevalence of depressive symptoms (51.2%, p = 0.001). Insulin-treated patients exhibited a higher burden of depression (46.9%) compared to those managed with oral hypoglycemic agents (p = 0.004). Furthermore, the presence of diabetes-related complications was strongly associated with depression, with 55.6% of patients with complications reporting depressive symptoms, compared to those without complications (p < 0.001). These findings suggest that depression in chronic diabetes is closely linked to disease severity, metabolic control, and long-term complications (Table 4). Table 1. Sociodemographic Characteristics of Study Participants (n = 240) Variable Frequency (%) Mean age (years) 56.4 ± 9.8 Male 132 (55.0) Female 108 (45.0) Urban residence 146 (60.8) Rural residence 94 (39.2) Table 2. Clinical Characteristics of Diabetes Variable Value Mean duration of diabetes (years) 9.6 ± 3.8 HbA1c ≥8% 142 (59.2%) On insulin therapy 98 (40.8%) Presence of complications 126 (52.5%) Table 3. Prevalence and Severity of Depression (PHQ-9) PHQ-9 Category Number (%) No depression 148 (61.7) Mild 46 (19.2) Moderate 30 (12.5) Severe 16 (6.6) Overall prevalence of depression (PHQ-9 ≥5) was 38.3%. Table 4. Association Between Depression and Clinical Variables Variable Depression Present (%) p-value HbA1c ≥8% 48.6 0.002 Diabetes ≥10 years 51.2 0.001 Insulin therapy 46.9 0.004 Complications present 55.6 <0.001

This study demonstrates a high prevalence of depressive symptoms among patients suffering from chronic diabetes, with nearly two-fifths of participants exhibiting clinically significant depression. These findings are consistent with recent international and Indian studies reporting prevalence rates between 30% and 45% [2,5,12]. Poor glycemic control emerged as a strong predictor of depression, corroborating evidence that sustained hyperglycemia contributes to neurobiological changes, inflammatory pathways, and psychosocial stress, thereby increasing depression risk [13]. Conversely, depression adversely affects self-management behaviors, creating a vicious cycle that worsens diabetes outcomes [14]. The significant association between longer disease duration and depression observed in this study aligns with findings by Roy et al. and Wang et al., who reported cumulative psychological burden with prolonged illness [5,15]. Insulin therapy and diabetes-related complications further amplified depression risk, likely reflecting disease severity and perceived loss of health autonomy. Despite the availability of effective screening tools, depression remains under-recognized in diabetic clinics, particularly in resource-limited settings. Integrating mental health services into diabetes care has been shown to improve glycemic outcomes, treatment adherence, and overall quality of life [16-20]. Strengths and Limitations Strengths • Use of a validated depression screening tool • Inclusion of clinically relevant diabetes variables • Adequate sample size Limitations • Cross-sectional design limits causal inference • Single-center study may limit generalizability • Use of screening rather than diagnostic psychiatric interviews

Depression is highly prevalent among patients suffering from chronic diabetes and is strongly associated with poor glycemic control, longer disease duration, insulin therapy, and diabetes-related complications. Routine screening for depression using simple validated tools such as PHQ-9 should be incorporated into diabetes management protocols. Integrated care models addressing both metabolic and mental health aspects are essential for improving long-term outcomes in this population.

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