The DIA-LINK Study is a prospective observational study analysing longitudinal associations and mediating links between diabetes distress (DD), depressive symptoms (DS) and glycaemic outcomes in people with type 1 diabetes (T1DM). A total of 200 people with T1DM with different levels of DD and DS are to be enrolled. At baseline, all participants are assessed for DD and DS, psychological and stress-related variables, self-reported self-management, HbA1c and inflammatory markers. This is followed by a 4-week ambulatory assessment period including continuous glucose monitoring (CGM), continuous activity tracking and daily event sampling regarding sleep, stress levels, mood and diabetes-related issues; additionally, cortisol levels are assessed on four days within this period. Three months after baseline, a follow-up assessment covers DD and DS levels, stress-related variables, self-reported self-management, HbA1c and final CGM assessment. The analyses aim to establish risk factors/protective factors regarding DD and DS, their relative impact on glycaemic outcomes and potential mediation of the associations by behavioural (e.g. self-management, physical activity), physical (e.g. heart rate variability, inflammatory activity) and mental variables (subjective stress level) in T1DM.
The DIA-LINK Study is a prospective observational study analysing longitudinal associations between diabetes distress (DD), depressive symptoms (DS) and glycaemic outcomes in people with type 1 diabetes (T1DM). A variety of behavioural, physical and mental variables are assessed to analyse the mediating links between DD, DS and glycaemia. A total of 200 people with T1DM are enrolled according to DD (PAID ≥ / \< 40) and DS (CES-D ≥ / \< 22) scores so that four groups (n = 50 persons each) with varying levels of DD and DS are established: 1. PAID \< 40 and CES-D \< 22 (no DD, no DS); 2. PAID ≥ 40 and CES-D \< 22 (DD, no DS); 3. PAID \< 40 and CES-D ≥ 22 (DS, no DD); 4. PAID ≥ 40 and CES-D ≥ 22 (DD and DS). At baseline, all participants are assessed for relevant psychological and stress-related variables (daily hassles, life events, diabetes-related problems and fears, coping styles, resilience, diabetes acceptance, depression) as well as self-reported diabetes self-management using validated self-report scales and interviews; HbA1c and selected markers of inflammation (hsCRP, IL-6, IL-18, IL1Ra) are analysed from venous blood samples. This is followed by a 4-week ambulatory assessment period including continuous glucose monitoring (CGM) (to establish time in range, glucose variability and times in hypo/hyperglycaemia), continuous activity tracking regarding general activity, movement, sleep and heart rate using a wristband as well as event sampling regarding sleep quality, stress levels, mood and diabetes-related issues four times daily using a smartphone app. Additionally, salivary cortisol levels are estimated on four consecutive days (each including a morning, afternoon and night time sample) within this period. Three months after baseline, a follow-up assessment is performed which includes self-report measures of DD and DS, stress-related variables and diabetes self-management, HbA1c estimation from venous blood samples and final CGM assessment over 14 days. The collected data are used to analyse risk factors/protective factors regarding DD and DS, their relative impact on glycaemic outcomes and potential mediation of the associations by behavioural (e.g. self-management, physical activity), physical (e.g. heart rate variability, inflammatory activity) and mental variables (subjective stress level) in T1DM. The findings shall be used to develop personalised interventions for people with diabetes and comorbid mental conditions (DD and DS).
Study Type
OBSERVATIONAL
Enrollment
208
There is no intervention or group-specific procedure per observation groups. Each of the 4 groups is monitored using ecological momentary assessment (EMA) for diabetes-specific problems, mood, stress, diabete distress via a smartphone app over 26 days. Study is observational/non-interventional; specific groups are enrolled to enable specific comparisons between people with/without depressive symptoms and/or diabetes distress; no specific interventions are offered to neither group.
Diabetes Center Mergentheim
Bad Mergentheim, Baden-Wurttemberg, Germany
Research Institute of the Diabetes Academy Mergentheim, Diabetes Center Mergentheim
Bad Mergentheim, Baden-Wurttemberg, Germany
Depressive symptoms
Depressive symptoms are assessed using the 20-item Center for Epidemiologic Studies Depression Scale (CES-D), covering 20 symptoms of depression. Frequencies of the symptoms during the past week are scored on a 4-point Likert scale (from 0 - "rarely or non of the time" to 3 - "most or all of the time"). Item scores are summed to a total score ranging from 0 to 60, whereby higher values reflect higher depressive symptoms. A cut-off point at ≥ 22 points (found to have the best likelihood ratio for detecting depression within the German population) is used to establish elevated depressive symptoms in this study.
Time frame: 3-month follow-up
Diabetes Distress
Diabetes Distress is assessed as using the 20-item Problem Areas In Diabetes Scale (PAID). 20 potential problems related to living with diabetes are rated on a 5-point Likert scale (from 0 - "not a problem" to 4 - "serious problem"). Item scores are summed/transformed to a total score ranging from 0 to 100, whereby higher values reflect higher diabetes distress. A cut-off point at ≥ 40 points is commonly used to establish high diabetes distress, so too in this study.
Time frame: 3-month follow-up
HbA1c
HbA1c (estimated in %-points; mmol/mol values are calculated thereof) is used as a measure of glycaemic levels during past 3 months. It is estimated from a venous blood sample using high performance liquid chromatography (Tosho G11 analyser; meeting International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) standard) in this study. Higher values indicate less optimal glycaemic control, and values above 7.5% (58 mmol/mol) are considered to indicate glycaemic levels in need of improvement.
Time frame: 3-month follow-up
"Time in range" of glucose levels
Percentage of glucose values measured using CGM ("FreeStyle Libre 2" glucose monitoring system) during 4-week ambulatory assessment which are between 70 and 180 mg/dl (out of all measured values). Note that although the expression "time in range (TIR)" suggests a time measure, this is in fact estimated as a percentage score.
Time frame: Continuous assessment over 4 weeks from baseline
Variability of glucose levels
Estimated by the coefficient of variation (range 0 to 1) of all glucose values measured using CGM ("FreeStyle Libre 2" glucose monitoring system) during the 4-week ambulatory assessment phase.
Time frame: Continuous assessment over 4 weeks from baseline
"Time in hypoglycaemia" of glucose levels
Percentage of glucose values measured using CGM ("FreeStyle Libre 2" glucose monitoring system) during 4-week ambulatory assessment phase which are below 70 mg/dl (out of all measured values). Note that although the expression "time in hypoglycaemia" suggests a time measure, this is in fact estimated as a percentage score.
Time frame: Continuous assessment over 4 weeks from baseline
"Time in hyperglycaemia" of glucose levels
Percentage of glucose values measured using CGM ("FreeStyle Libre 2" glucose monitoring system) during 4-week ambulatory assessment phase which are over 180 mg/dl (out of all measured values). Note that although the expression "time in hyperglycaemia" suggests a time measure, this is in fact estimated as a percentage score.
Time frame: Continuous assessment over 4 weeks from baseline
Activity time
Activity time (in h/day) is measured continuously during the 4-week ambulatory assessment phase using a wearable health tracker/wristband ("Garmin vivosmart 4").
Time frame: Continuous assessment over 4 weeks from baseline
Sleep time
Sleep time (in h/day) is measured continuously during the 4-week ambulatory assessment phase using a wearable health tracker/wristband ("Garmin vivosmart 4").
Time frame: Continuous assessment over 4 weeks from baseline
Heart rate (variability)
Heart rate (in beats/minute) is measured continuously during the 4-week ambulatory assessment phase using a wearable health tracker/wristband ("Garmin vivosmart 4"). Heart rate variability is calculated thereof using the coefficient of variation.
Time frame: Continuous assessment over 4 weeks from baseline
Sleep quality
Sleep quality during the past night is assessed daily during the 4-week ambulatory assessment phase using items adapted from the Pittsburgh Sleep Quality Index (PSQI) for use in an ecological momentary assessment (EMA) survey via smartphone. The items assess/enable estimation of 1. subjective sleep quality; 2. sleep latency; 3. sleep duration; and 4. sleep efficiency. Each aspect is scored on a 4-point scale from 0 (no problem) to 3 (great problem), and scores are summed to a total ranging from 0 to 12, so that higher scores reflect worse overall sleep quality.
Time frame: Daily assessment over 4 weeks from baseline
Stress level
Stress level is assessed four times daily during the 4-week ambulatory assessment phase assessed using the single item "How stressed are you feeling right now?" and a Likert scale from 0 - "not at all stressed" to 10 - "very strongly stressed" in an ecological momentary assessment (EMA) survey via smartphone.
Time frame: Daily assessment over 4 weeks from baseline
Mood: Hedonic tone
Mood is assessed twice daily during the 4-week ambulatory assessment phase using selected items from the University of Wales Institute of Science and Technology (UWIST) Mood Adjective Checklist (UMACL) in an ecological momentary assessment (EMA) survey via smartphone. 12 of the 29 UMACL items were selected based on their significant associations with glycaemic outcomes from CGM assessment (own data set); each four of them reflect positive and negative hedonic tone and energetic and tense arousal. Responses are given on a four-point Likert scale (0 - "definitely not" / 1 - "slightly not" / 2 - "slightly" / 3 - "definitely) reflecting the presence or absence of each aspects. Item scores are summed/averaged to scale scores (from 0 to 3) reflecting hedonic tone and arousal levels; higher scores reflect higher hedonic tone and arousal levels, respectively.
Time frame: Daily assessment over 4 weeks from baseline
Mood: Arousal
Mood is assessed twice daily during the 4-week ambulatory assessment phase using selected items from the University of Wales Institute of Science and Technology (UWIST) Mood Adjective Checklist (UMACL) in an ecological momentary assessment (EMA) survey via smartphone. 12 of the 29 UMACL items were selected based on their significant associations with glycaemic outcomes from CGM assessment (own data set); each four of them reflect positive and negative hedonic tone and energetic and tense arousal. Responses are given on a four-point Likert scale (0 - "definitely not" / 1 - "slightly not" / 2 - "slightly" / 3 - "definitely) reflecting the presence or absence of each aspects. Item scores are summed/averaged to scale scores (from 0 to 3) reflecting hedonic tone and arousal levels; higher scores reflect higher hedonic tone and arousal levels, respectively.
Time frame: Daily assessment over 4 weeks from baseline
Diabetes-specific problems
Diabetes-specific problems are assessed daily during the 4-week ambulatory assessment phase using six items adapted from the Problem Areas In Diabetes Scale and additional items in an ecological momentary assessment (EMA) survey via smartphone. Responses are given on a Likert scale from 0 - "not at all" to 10 - "very strong". Item scores are averaged to a scale ranging from 0 to 10, whereby higher scores indicate greater problems.
Time frame: Daily assessment over 4 weeks from baseline
Cortisol
Cortisol level (in μg/dl) is estimated from saliva samples collected at fixed day times (morning; afternoon; late evening) on four consecutive days (Sat/Sun/Mon/Tue) during ambulatory assessment period. Collection date within 4 week-period is from the beginning of the third week (approx. 2 weeks after baseline). Samples are analysed using electrochemiluminescence (Cobas 6000 analyser).
Time frame: 2 weeks after baseline
Marker of inflammation #1: high sensitivity C-reactive protein (hsCRP)
Estimated from venous blood sample (fasting blood collection) in mg/dl.
Time frame: Baseline
Marker of inflammation #2: interleukin-6 (IL-6)
Estimated from venous blood sample (fasting blood collection) in pg/ml.
Time frame: Baseline
Marker of inflammation #3: interleukin-18 (IL-18)
Estimated from venous blood sample (fasting blood collection) in pg/ml.
Time frame: Baseline
Marker of inflammation #4: interleukin-1 receptor antagonist (IL-1Ra)
Estimated from venous blood sample (fasting blood collection) in pg/ml.
Time frame: Baseline
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