Evaluation of the prevalence of the most common psychiatric disorders in patients with type 2 diabetes mellitus using the patient health questionnaire: results of the cross-sectional “DIA2PSI” study

Monocentric cross-sectional study, conducted at the Fondazione Policlinico Universitario Agostino Gemelli IRCCS, UCSC, Rome, Italy (FPUAG).

A full description of the protocol used in the present study is provided in the Online Resource 1.

In brief, between October 2020 and November 2021 a sample of consecutive outpatient clinic attendees with T2D at the Diabetes Care Unit of the FPUAG was invited to participate in the study, with the aim of including 184 people with T2D.

Inclusion criteria were age between 18 and 85 years and diagnosis of T2D [21]. Exclusion criteria were diagnosis of Type 1 Diabetes mellitus (T1D); inability to complete the survey tools because of cognitive difficulties; to be very sick and unable to read and understand Italian. Women who were pregnant or had given birth in the last 6 months were also excluded.

Prior to interview, the site investigators fulfilled an information form for each patient. This form included socio-demographic information such as age, gender, civil status, residence location, educational level, and smoke status. T2D-specific information and anthropometric profile have been registered: duration of T2D, height, weight and BMI at diagnosis of T2D; actual height weight and BMI; antidiabetic drugs or insulin prescription; family history of T2D and history of T2D complications (cardiovascular disease, retinopathy, peripheral neuropathy, and renal disease); hypertension. Measurements of blood pressure, HbA1c, were also recorded. A section on past psychiatric history and on awareness of the importance of lifestyle changes and of mental health with respect to weight control and the prevention of physical diseases is also contained within the form; for more details, see Online resource 2. The patient's medical history was obtained before the PHQ administration to adequately attribute the presence of any physical symptoms to a medical condition or to the somatoform disorder. Any prescribed medicine for mental health problem was noted, as was any diagnosis or therapy of any psychiatric disorder. Patients were queried if they lived in a rural or an urban area and declared their highest level of education. Marital status was defined as married/co-habiting vs being single/widowed/divorced.

Each participant was requested to complete the Patient Health Questionnaire. The Italian full version of the PHQ [22] was used for psychiatric screening, as it covers the CPDs. The PHQ is a self-administered questionnaire that allows to evaluate the presence of specific disorders: major depressive disorder, other depressive disorders, panic attack disorder, other anxiety disorders, bulimia nervosa, binge eating disorder, dependence or alcohol abuse.

In this study, all the sections, from 1 to 11, of the official Italian version of the PHQ were used.

Subjects diagnosed with any psychiatric disorders were directed to consult their physician or the Psychiatric Unit of FPUAG for further evaluation and treatment.

The study protocol was approved by the Ethics Committee (EC) of the FPUAG Università Cattolica del Sacro Cuore, on 08/08/2020 with number ID 3298 and protocol number 0040703/20. All procedures performed in the study were in accordance with the ethical standards of the institutional committee and with the Declaration of Helsinki and its later amendments. All participants signed a written informed consent form.

Sample size calculation was performed assuming an expected prevalence of psychiatric disorders of 37.5%, setting up an accuracy of 7% and a confidence level of 97%, thus calculating 184 patients to administer the PHQ. The expected prevalence was estimated from a previous study carried out in T2D patients [23].

Included patients were described in clinical and demographic characteristics through descriptive statistics techniques. Continuous variables had been checked for normality with Shapiro–Wilk test. Therefore, normally distributed data were expressed as mean and standard deviation (SD), and non-normally with median and first and third quartiles (q1–q3). Dichotomous variables, categorical variables, and scores were expressed as numbers and percentages.

Primary outcome was the prevalence of common psychiatric disorders in patients with T2D assessed through the Patient Health Questionnaire.

The data associated with the study are available from the corresponding author on reasonable request.

The demographic characteristics of the patients interviewed are reported in Table 1. Patients were 118 men (64.1%) and 66 women (35.9%), the median age was 67 years (q1–q3: 59–64), and 139 were married/co-habiting (75.5%). About the residence location, 116 (63.1%) were living in Urban location, while 68 (36.9%) in rural area. It was also recorded that patients had an average 11-year study education (± 4 years of study) and 162 (88.0%) were no current smoker.

The population evaluated have (Table 2): T2D on average from 10 years (q1–q3: 5–17). The median weight recorded was 80 kg (69–87) with a median height of 170 cm (162–176), median BMI 27 kg/m2 (25–30), of which 53 patients (28.8%) had a BMI in the obesity range. The weight and BMI of the patients at the time of T2D diagnosis were also collected and were: median weight 80 kg (q1–q3: 70–92) median BMI: 29 kg/m2 (25–31), of which 73 patients (39.7%) had a BMI in the obesity range. Additional values collected at the time of test administration were: median HbA1c and pharmacological therapy. Patients had median HbA1c of 6.8 (q1–q3: 6.1–7.6), 51 mmol/mol, and 146 patients (79.4%) were taking some type of oral and injectable (non-insulin) antidiabetic agents for the treatment of T2D, while 64 (34.8%) patients were taking insulin. A total number of 118 (64.1%) persons have at the time of the interview at least one complication related to T2D: 81 (44%) patients have CVD, 32 (17.4%) had neuropathy, 57 (40%) patients have retinopathy, 27 (14.7%) patients have Chronic Kidney Disease (CKD), and 140 (76.1%) suffer from hypertension.

The prevalence of the different psychiatric disorders evaluated through the PHQ is provided in Fig. 1–2 and Table 3.

Of the sample examined, 79 people out of 184 tested positives for the PHQ, namely 42.9%, and 25.6% tested positive for a depressive disorder (percentage derived from the sum of Other Depressive Syndrome and Major Depressive Syndrome). The last question of the PHQ is: "If you checked off any problems on this questionnaire, how difficult have these problems made it for you to do your work, take care of things at home, or get along with other people?" to this question alternatives answer are: not difficult at all, somewhat difficult, very difficult, extremely difficult. 144 (78.3%) patients answered: not difficult at all.

In addition to the collection of socio-demographic data, and to the administration of the PHQ, patients were asked about their awareness of the importance of weight loss in the remission of T2D [24, 25] and if they “are aware about the importance of mental health in controlling body weight and in prevention of physical diseases?”.

On the importance of lifestyle changes in the T2D remission, 174 people (94.6% of patients) replied that they received this information from their treating physician, while the percentage dropped to 134 patients (72.8%) when they were asked if, besides the importance of physical health, they know the importance of mental health in body weight control and prevention of physical diseases.

The patients were also asked whether they presented a psychiatric diagnosis in medical history, or if they had ever been treated by a psychiatrist or a psychotherapist and/or if they ever took psychopharmacological treatments in the past. The 46 patients (25.0%) had been treated by a psychiatrist or psychotherapist, and among them, 38 patients (20.6%) ​​had undertaken psychopharmacological treatments.

Demographic and lifestyle predictors of current common psychiatric disorder are shown in Table 4 in Online resource 3.

Among all demographic and lifestyle variables we have analyzed, our results showed that female in comparison with males had 72% higher probability of testing positive to PHQ (OR = 1.72; 95%CI: 0.94–3.17), even if the result was not significant (p = 0.08). For every increase of 1 year in patients’ age, we noticed a 2% of reduction in developing positivity to the questionnaire (OR = 0.98; 95%CI: 0.95–1.00), but the result is not statistically significant (p = 0.07). BMI is a risk factor associated with a greater likelihood of testing positive for PHQ, indeed for every 1-point increase in current BMI there is a 7% increased risk (OR = 1.07; 95%CI: 1.00–1.14, p = 0.04), and for every 1-point increase in BMI at diagnosis the OR is equal to 1.05 (95%CI: 1.00–1.10, p = 0.06). Urban residence location, in comparison with rural, showed a 42% probability reduction in association with CPDs (OR = 0.58; 95%CI: 0.31–1.06), but it was not statistically significant (p = 0.07). Civil status and educational level did not show significant results.

Diabetes specific and psychosocial predictors of current common psychiatric disorder are shown in Table 5–6 in Online resource 3. Among those, antidiabetic drugs (non-insulin) use was associated with a 30% reduction in probability of having some common psychiatric disorder (OR = 0.70; 95%CI:0.34–1.43, p = 0.32), but the result was not statistically significant. Patients taking insulin, in comparison with patients that did not, had an 89% increase in the likelihood of testing positive to the PHQ (OR = 1.89; 95%CI: 1.02–3.49, p = 0.04), and this finding is likely related to the severity of the diabetic disease. Other interesting results are that patients who had implemented lifestyle changes showed a 62% odds reduction in being diagnosed of psychiatric disorders (OR = 0.38; 95%CI: 0.18–0.79, p < 0.01), patients who are aware that mental health is linked to body health had a 46% odds reduction (OR = 0.54; 95%CI: 0.28–1.04, p = 0.07), and patients who had Previous or actual Pharmaco-PSY treatment had a 246% probability increase in testing positive to the PHQ (OR = 2.46; 95%CI: 1.19–5.12, p = 0.02).

The population analyzed was mainly Caucasian, which limits generalization to non-Caucasian populations such as South Asians, who tend to develop T2D with less weight gain. Quality and robustness of our findings are limited by cross-sectional study design, restricted sample size, monocentric study, and the lack of multivariable analysis. Also, as with any diagnostic test, the PHQ does not detect all cases of mental disorders.