Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycaemia resulting from impaired insulin secretion, insulin action, or both. Its management requires lifelong medication, dietary regulation, physical activity, glucose monitoring, and prevention of acute and chronic complications. These demands may impose considerable psychological, social, occupational, and financial burdens on affected individuals.

Depressive symptoms are common among people with diabetes mellitus, and the relationship between the two conditions is potentially bidirectional.[1–6] The continuous demands of diabetes self-management, fear of hypoglycaemia, disease progression, treatment costs, disability, and complications may increase psychological distress. Conversely, depression may reduce motivation for self-care, impair medication adherence, adversely affect glycaemic control, and contribute to poorer quality of life and increased healthcare utilization.

Despite its clinical importance, depression may remain unrecognized during routine diabetes care because symptoms such as fatigue, sleep disturbance, appetite changes, and reduced concentration may overlap with manifestations of diabetes or its complications. The Patient Health Questionnaire-9 is a brief and widely evaluated instrument for assessing depressive symptoms during the preceding two weeks.[8–12] A score of ≥10 is commonly used to identify clinically significant depressive symptoms requiring further evaluation. However, the PHQ-9 is a screening tool and does not replace a structured psychiatric assessment.

The prevalence of depressive symptoms among people with diabetes varies according to the study population, healthcare setting, screening method, socioeconomic circumstances, diabetes duration, treatment modality, glycaemic control, complications, and comorbidities. Evidence from tertiary, urban, and rural healthcare settings is therefore important for estimating the burden of depression and identifying patients at increased risk.

The present study aimed to determine the prevalence and severity of depressive symptoms among adults with diabetes mellitus attending non-communicable disease clinics and to assess their association with selected clinical characteristics.

Aim

To assess the prevalence and clinical correlates of depressive symptoms among adults with diabetes mellitus attending non-communicable disease clinics.

Objectives

To estimate the prevalence and severity distribution of depressive symptoms among adults with diabetes mellitus & clinical profile using the Patient Health Questionnaire-9.

Study design and setting An institution-based cross-sectional study was conducted among adults with diabetes mellitus attending the non-communicable disease clinics of a tertiary-care hospital, an Urban Health Training Centre, and a Rural Health Training Centre in Department of Psychiatry, Maheshwara Medical College. The study was conducted from March 2023 to February 2024. Study population Adults aged ≥18 years with a documented diagnosis of type 1 or type 2 diabetes mellitus who attended the selected clinics for follow-up and provided informed consent were included. Patients who declined participation, were critically ill or medically unstable, were unable to communicate, or could not reliably complete the questionnaire were excluded. Selection of study sites and sampling The three study sites were selected purposively based on the availability of established non-communicable disease clinics. The sample was proportionally allocated across the three sites. At each site, the first eligible participant was selected by lottery, after which eligible participants were enrolled consecutively until the allocated sample was reached. Study variables The primary outcome was probable depression, defined as a Patient Health Questionnaire-9 score of ≥10. The explanatory variables included age, gender, marital status, residence, family type, education, socioeconomic status, number of family members, type and duration of diabetes, treatment received, diabetic complications, chronic comorbidities, and family history of depression. Data-collection instrument Data were collected using a pretested, semi-structured questionnaire administered through participant interview and review of available clinical records. The questionnaire captured sociodemographic characteristics, diabetes history, treatment duration, current treatment, diabetic complications, comorbidities, family history of depression, and depressive symptoms. Patient Health Questionnaire-9 Depressive symptoms during the preceding two weeks were assessed using the PHQ-9. Each of the nine items was scored from 0 to 3, giving a total score of 0–27. Scores were categorized as: PHQ-9 score Severity category 0–4 Minimal or no depressive symptoms 5–9 Mild depressive symptoms 10–14 Moderate depressive symptoms 15–19 Moderately severe depressive symptoms 20–27 Severe depressive symptoms A score of ≥10 was considered indicative of clinically significant depressive symptoms or probable depression. The PHQ-9 was used as a screening instrument and not as a substitute for psychiatric diagnosis. Operational definitions Diabetes mellitus was defined as a documented diagnosis of type 1 or type 2 diabetes mellitus. The diagnostic criteria considered were fasting plasma glucose ≥126 mg/dL, two-hour plasma glucose ≥200 mg/dL during a 75-g oral glucose tolerance test, glycated haemoglobin ≥6.5%, or random plasma glucose ≥200 mg/dL in the presence of classic hyperglycaemic symptoms.[7] Any depressive symptoms were defined as a PHQ-9 score of ≥5, while probable depression was defined as a score of ≥10. Comorbidity was defined as any chronic disease coexisting with diabetes mellitus. A diabetic complication was defined as any documented acute or chronic complication attributable to diabetes. Duration of diabetes and duration of diabetes treatment were categorized as ≤5 years or >5 years. Socioeconomic status was classified using the modified BG Prasad classification applicable during the study period. Data-collection procedure Eligible participants were approached during scheduled clinic visits. After informed consent, sociodemographic and clinical data were obtained through interview and review of clinical records. The PHQ-9 was administered during the same encounter. Participants who screened positive for probable depression were referred for further mental-health assessment and management. Statistical analysis Data were analyzed using IBM SPSS Statistics for Windows, version 26.0. Categorical variables were summarized as frequencies and percentages. Continuous variables were summarized using the mean and standard deviation or the median, as appropriate. The prevalence of probable depression was calculated as the proportion of participants with PHQ-9 scores ≥10. Associations between categorical variables and probable depression were assessed using the Pearson chi-square test or Fisher’s exact test, as appropriate. Binary logistic regression was used to estimate crude odds ratios and corresponding 95% confidence intervals. All statistical tests were two-sided, and a P value <0.05 was considered statistically significant.

Sociodemographic characteristics

A total of 400 participants were included in the analysis. The majority were male (282, 70.5%), while 118 participants (29.5%) were female. Most participants were older than 40 years (321, 80.3%), and 79 (19.8%) were aged 40 years or younger.

A total of 343 participants (85.8%) were married and 57 (14.3%) were unmarried. Urban and rural residents were equally represented, with 200 participants (50.0%) in each category. Nuclear families accounted for 239 participants (59.8%), while 161 (40.3%) belonged to joint families.

Primary education was the most frequently reported educational level, observed in 223 participants (55.8%). Fifty-five participants (13.8%) had completed higher secondary education, 12 (3.0%) were graduates, and 110 (27.5%) had no formal education. According to the modified BG Prasad classification, 220 participants (55.0%) belonged to the lower socioeconomic class and 180 (45.0%) belonged to the upper socioeconomic class. Most participants lived in households containing five or fewer members (354, 88.5%) (Table 1).

Table 1. Sociodemographic characteristics of the study participants (N = 400)

*Socioeconomic status was classified according to the modified BG Prasad socioeconomic classification. Percentages may not total exactly 100.0 because of rounding.

The study population was predominantly male, older than 40 years, married, and living in households with five or fewer members.

Clinical characteristics

Type 2 diabetes mellitus was present in 338 participants (84.5%), while 62 (15.5%) had type 1 diabetes mellitus. The duration of diabetes treatment was five years or less in 274 participants (68.5%) and more than five years in 126 (31.5%).

A history of acute or chronic diabetic complications was documented in 135 participants (33.8%), whereas 265 (66.3%) had no reported complications. Other chronic comorbidities were present in 164 participants (41.0%). A family history of depression was reported by 27 participants (6.8%).

Sixty-eight participants (17.0%) were receiving insulin, while 332 (83.0%) were being treated with oral hypoglycaemic drugs (Table 2).

Table 2. Clinical characteristics of the study participants (N = 400)

Most participants had type 2 diabetes mellitus, had received treatment for five years or less, and were being managed with oral hypoglycaemic drugs.

Distribution of depressive symptoms

Minimal or no depressive symptoms were observed in 102 participants (25.5%), while 65 (16.3%) had mild depressive symptoms. Moderate depressive symptoms were identified in 112 participants (28.0%), moderately severe symptoms in 117 (29.3%), and severe symptoms in 4 (1.0%).

A total of 298 participants had PHQ-9 scores of ≥5, corresponding to a prevalence of any depressive symptoms of 74.5%. Probable depression, defined as a PHQ-9 score of ≥10, was identified in 233 participants, giving an overall prevalence of 58.3% (Table 3).

Table 3. Distribution of depressive symptoms according to PHQ-9 severity (N = 400)

Summary classification

More than half of the participants screened positive for probable depression, and moderately severe depressive symptoms were the most frequent individual severity category.

Association between clinical characteristics and probable depression

Probable depression was present in 49 of the 62 participants with type 1 diabetes mellitus (79.0%), compared with 184 of the 338 participants with type 2 diabetes mellitus (54.4%). Participants with type 1 diabetes had higher crude odds of probable depression than those with type 2 diabetes mellitus (COR: 3.15; 95% CI: 1.65–6.03; P<0.001).

Among participants receiving insulin, 57 of 68 (83.8%) screened positive for probable depression, compared with 176 of the 332 participants receiving oral hypoglycaemic drugs (53.0%). Insulin-treated participants had significantly higher crude odds of probable depression (COR: 4.59; 95% CI: 2.33–9.07; P<0.001).

Probable depression was identified in 123 of the 135 participants with diabetic complications (91.1%), compared with 110 of the 265 participants without complications (41.5%). The presence of diabetic complications was associated with markedly increased crude odds of probable depression (COR: 14.44; 95% CI: 7.61–27.42; P<0.001).

Among participants with other chronic comorbidities, 109 of 164 (66.5%) had probable depression, compared with 124 of the 236 participants without comorbidities (52.5%). Comorbidity was associated with increased crude odds of probable depression (COR: 1.79; 95% CI: 1.18–2.70; P=0.005).

Probable depression was present in 106 of the 126 participants with diabetes for more than five years (84.1%), compared with 127 of the 274 participants with a duration of five years or less (46.4%). A diabetes duration of more than five years was associated with substantially higher crude odds of probable depression (COR: 6.13; 95% CI: 3.60–10.46; P<0.001) (Table 4).

Table 4. Association between clinical characteristics and probable depression (N = 400)

Abbreviations: CI, confidence interval; COR, crude odds ratio; PHQ-9, Patient Health Questionnaire-9.

Type 1 diabetes, insulin treatment, diabetic complications, comorbidities, and diabetes duration exceeding five years were significantly associated with probable depression, with diabetic complications showing the strongest crude association.

FIGURE 1 — Sociodemographic characteristics

FIGURE 2 — Clinical characteristics

FIGURE 3 — Depressive symptom severity

FIGURE 4 — Clinical depression prevalence

FIGURE 5 — Depression according to diabetes type

FIGURE 6 — Depression according to treatment received

FIGURE 7 — Depression according to diabetic complications

FIGURE 8 — Depression according to comorbidity status

FIGURE 9 — Depression according to diabetes duration

The present study demonstrated a substantial burden of depressive symptoms among adults receiving follow-up care for diabetes mellitus. Nearly three-quarters of participants had at least mild depressive symptoms, while 58.3% screened positive for probable depression using a PHQ-9 cutoff score of ≥10. Moderately severe depressive symptoms constituted the most frequent individual category. The prevalence of probable depression was higher than that reported in several previous studies conducted among people with diabetes.[1,3,6] Birhanu et al. reported a prevalence of 41.6% among patients attending public hospitals in Southwest Ethiopia.[6] Differences between studies may reflect variations in healthcare settings, patient characteristics, diabetes duration, socioeconomic conditions, complication burden, screening instruments, and diagnostic thresholds. As the PHQ-9 is a screening instrument, the prevalence observed in the present study represents clinically significant depressive symptoms requiring further assessment rather than psychiatrist-confirmed major depressive disorder.[8–12] Participants with type 1 diabetes had approximately three times higher crude odds of probable depression than those with type 2 diabetes. The intensive self-management required in type 1 diabetes, including lifelong insulin administration, frequent glucose monitoring, dietary planning, and vigilance for hypoglycaemia, may contribute to psychological distress.[4,5] However, differences in age at diagnosis, disease duration, treatment burden, and complication profile may partly explain this association. Insulin-treated participants also had higher odds of probable depression than those receiving oral hypoglycaemic drugs. Fear of injections and hypoglycaemia, repeated monitoring, treatment costs, and perceived disease severity may increase emotional burden. Insulin use may also indicate longer disease duration, type 1 diabetes, inadequate glycaemic control, or advanced disease and should therefore not be interpreted as a direct cause of depression.[24] A duration of diabetes exceeding five years was strongly associated with probable depression. Prolonged exposure to medication use, dietary restrictions, glucose monitoring, treatment fatigue, healthcare expenditure, and fear of complications may adversely affect psychological well-being.[6,18] Emotional and psychological assessment should therefore be repeated throughout the course of diabetes rather than being limited to the time of diagnosis.[19] Diabetic complications demonstrated the strongest crude association with probable depression. Complications may cause chronic pain, visual impairment, reduced mobility, occupational limitations, repeated hospitalization, financial strain, and fear of disability or amputation. Previous studies have similarly reported associations between depression and retinopathy, neuropathy, nephropathy, peripheral vascular disease, coronary artery disease, and diabetic foot disease.[20–22] The relationship may be bidirectional, as complications may contribute to depression, while depression may impair self-care and glycaemic control. Participants with other chronic comorbidities also had higher odds of probable depression. Managing multiple illnesses may increase medication burden, dietary complexity, healthcare expenditure, clinic attendance, and functional limitations.[1,3,16] The weaker association compared with diabetic complications may reflect variation in the nature and severity of the comorbid conditions included. These findings support the integration of mental-health assessment into routine diabetes care. Patients with type 1 diabetes, insulin treatment, long-standing disease, diabetic complications, or multiple comorbidities may particularly benefit from periodic screening. Positive PHQ-9 results should be followed by clinical assessment, review of self-harm risk, appropriate counselling, and referral to mental-health services when indicated. Strengths and limitations The study included participants from tertiary, urban, and rural healthcare facilities and used the widely evaluated PHQ-9 to assess depressive symptom severity. It also examined clinically relevant factors, including diabetes type, treatment, duration, complications, and comorbidities. However, the cross-sectional design prevented determination of causality or temporal sequence. Facility-based recruitment may limit generalizability to the wider community. The PHQ-9 is a screening instrument rather than a diagnostic interview, and some information obtained through participant interviews may have been affected by recall or reporting bias. In addition, the reported associations were crude and may have been influenced by confounding factors.

Depressive symptoms were common among adults with diabetes mellitus attending non-communicable disease clinics, with more than half screening positive for probable depression.

Type 1 diabetes mellitus, insulin treatment, diabetic complications, chronic comorbidities, and diabetes duration exceeding five years were associated with higher crude odds of probable depression. The strongest association was observed among participants with diabetic complications.

Periodic depression screening should be incorporated into comprehensive diabetes care, particularly for patients with long-standing disease, insulin use, comorbidities, or established complications. Individuals with elevated PHQ-9 scores should receive appropriate clinical assessment and referral.

RECOMMENDATIONS

1. Depression screening should be integrated into routine diabetes follow-up services with appropriate referral and treatment pathways.
2. Healthcare personnel should be trained in administering and interpreting the PHQ-9.
3. Patients with long-standing diabetes, insulin treatment, complications, or multiple comorbidities should receive focused psychological assessment.
4. Positive PHQ-9 screens, particularly responses indicating self-harm risk, should be followed by prompt clinical evaluation.
5. Multicentre longitudinal studies incorporating glycaemic control, treatment adherence, diabetes-related distress, and structured psychiatric assessment are recommended.

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