Table 1 Description of questionnaires

17-item Diabetes Distress Scale (DDS-17) [16]

Assesses problems and hassles concerning diabetes during the past 1 month. Four sub-scales: emotional burden (EB), physician-related distress (PD), regimen-related distress (RD) and diabetes-related interpersonal distress (ID).

Likert scale scores from 1 (not a problem) to 6 (a very serious problem). Total scale score plus 4 sub scale scores. A mean item score of ≥ 3 (severe distress) is considered a level of distress worthy of clinical attention [74].

The Brief Illness Perception Questionnaire (BIPQ) [75]

The scale has nine items providing simple and rapid assessment of illness perceptions. It measures patients’ cognitive and emotional representations of their illness including consequences, timeline, personal control, treatment control, identity, coherence, concern, emotional response, and causes.

Eight items are rated using a 0-to-10 response scale except the item 9 on causal question. For example when measuring understanding about the illness, the scale ranges from 0 (don’t understand at all) to 10 (understand very clearly). The causal open-ended response item asks patients to list the three most important causal factors for their diabetes.

Patient Health Questionnaire (PHQ-9) [76, 77]

Nine items refer to symptoms experienced by patients during the 2 weeks prior to answering the questionnaire in making diagnosis and assessing severity of depression.

Scores range from 0 to 27, as each of the nine items is scored from 0 (not at all) to 3 (nearly every day). PHQ-9 scores of 5, 10, 15, and 20 represents mild, moderate, moderately severe, and severe depression, respectively.

World Health Organization Quality of Life- Brief (WHOQOL-BREF) [78, 79]

Twenty-four items assessing health-related quality of life in the past four weeks. It produces four quality of life domains and scores, 1) Physical domain, 2) Psychological domain, 3) Social Relationships domain and 4) Environment domain. Two extra items examine separately: question 1 asks about an individual’s overall perception of quality of life and question 2 asks about an individual’s overall perception of his or her health.

Items have Likert scale from 1 to 5. Higher scores denote higher quality of life. The mean score of items within each domain is used to calculate the domain score. Mean scores are then multiplied by 4 in order to make domain raw scores comparable with the scores used in the WHOQOL-100.

Diabetes Management Self Efficacy Scale (DMSES) [80–82]

Twenty items, to evaluate patients’ confidence in managing their disease in terms of blood glucose, diet, and exercise.

Scores range from 10 if the respondents “certainly can do” to 0 if they “cannot do at all.” Total scores range from 0 to 200.

Summary of Diabetes Self-Care Activities (SDSCA) [81, 83, 84]

Eleven items that measure patients’ daily activities during the past 7 days in relation to diet, exercise, blood sugar, foot care and smoking behaviour.

Ten items are rated on an 8-point Likert scale, measuring how many days an activity is performed in the last week. One item measures smoking status (yes/no) and the amount of cigarettes smoked in the last week. Each of the domains is measured separately.

Positive affects subscale of the Center for Epidemiologic Studies Depression Scale (PA-CESD) [85]

Four items on positive affects such as self-esteem, hopeful, happy and enjoying life.

Items are assessed for the past 1 week on a scale of four possible responses; 0) less than 1 day, 1) 1–2 days, 2) 3–4 days; and 3) 5–7 days. Higher scores indicate more positive feelings