Type 1 diabetes is a chronic disease requiring complex and demanding treatment based on insulin therapy. Patient is obliged to perform daily diabetes self-management tasks, as performing regular glucose checks, exercising, following proper diet to maintain good metabolic control. The treatment goals include appropriate glycated hemoglobin (HbA1c) < 7% due to low, not high blood glucose variability, prevention of acute and chronic complications such as microvascular retinopathy, chronic kidney disease, neuropathy or macrovascular myocardial infarction or stroke (1). The treatment regimen is usually individualized, with respect to patient’s behaviours, needs, mental skills as well as social and economic status. Different educational approaches are used to implement therapeutic regimens, most of them comprising issues of patient empowerment (2, 3). Since the results of The Diabetes Control and Complications Trial have been published in 1993, a need for good metabolic control in terms of prevention of chronic complications was emphasized in diabetes management guidelines (4). Then, intensive functional insulin therapy has been recommended as a method for well-educated patients, when an insulin dose is calculated on a basis of actual glucose level, amount of carbohydrate in a meal and planned physical activity. However, adjusting the rules of treatment to the existing lifestyle may be a source of emotional distress and fatigue, that in turn may affect motivation and ability to perform necessary self-management tasks, resulting in poorer metabolic control. High levels of diabetes-related stress are also likely to reduce the patient’s quality of life. As a result, the risk of disease complications may be increased. Moreover, widely understood non-diabetes-related stress, i.e. due to social or economic status may influence treatment compliance and metabolic control in diabetic patients. Therefore it is important to early diagnose diabetes- and non-diabetes-related distress and to understand factors determining the feeling of fatigue. Still, not every subject diagnosed with chronic disease, such as diabetes, declares fatigue and decreased quality of life. Fatigue as a complaint is common among general population. According to Eurobarometer Mental Health, 27% of responders from 27 European countries reported to be “tired most of the time” (5). However, the term fatigue is multidimensional, includes physiological, psychological and environmental aspects and origins (6).

The aim of this study was to assess fatigue in subjects with longstanding type 1 diabetes.

A total of 312 patients were identified as eligible from our outpatient clinic to participate in the study. Of these, 1 refused participation because of lack of interest, 26 failed to complete baseline data. Finally, 285 subjects were included, 53% of women. The median age was 43 years [interquartile range (IQR): 34-52], type 1 diabetes duration over 20 years [median duration time 26 years (IQR: 22-31)], median age at onset 14 years (IQR: 9-23), HbA1c 7.8% (IQR: 7.1-8.9). We excluded patients diagnosed with chronic complications causing disability, such as blindness, end stage renal disease, manifested by estimated glomerular filtration rate (eGFR) < 15 ml/min/1.72 m² [eGFR was calculated using Modification of Diet in Renal Disease (MDRD) study equation], history of limb amputation or painful peripheral neuropathy as irreversible disability or chronic pain are recognized factors of chronic distress and fatigue themselves. We also established the upper age border at 60 years, as older patients are more often retired which can affect their questionnaire answers concerning lifestyle. 191 subjects had a positive history of using reusable needles requiring sterilization for insulin injections, 225 subjects a history of using bovine or porcine insulin.

To assess fatigue participants were asked to complete the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF) and to answer the question: “Do you feel fatigue due to living with diabetes?”. MFSI-SF is a 30-item self-report measure designed to assess multidimensional aspects of fatigue that include general, physical, emotional, mental fatigue and vigor. The vigor subscale score is subtracted from the sum of the 4 fatigue subscales to yield a total fatigue score. Subscale scores range from 0 to 24, and MFSI-SF total scores range from -24 to 96, with higher scores indicating more fatigue (7). The scale has no established cut-off scores, although Stein et al. showed that MFSI-SF Total scores above 0.85 represented significant fatigue (8). While the validity and reliability of MFSI-SF was shown on cancer patients, it is not a disease-specific fatigue scale and may be used in other chronic diseases (9, 10). Participants of our study fulfilled some additional questionnaires assessing their personality, depressive symptoms, coping with diabetes. We based the assessment of personality on Neuroticism Extraversion Openness Five-Factor Inventory (NEO-FFI) by Costa and McCrae (11, 12), a 60-item psychological personality inventory measuring The Big Five personality traits: Extraversion, Agreeableness, Conscientiousness, Neuroticism, and Openness to Experience. The Beck Depression Inventory, a 21-question multiple-choice tool was used for screening for emotional and physical symptoms of depression. We also used The Problem Areas in Diabetes Questionnaire (PAID), a 20-item scale measuring and classifying diabetes-related emotional distress into subgroups of: emotional burden, physician-related distress, regimen distress and interpersonal distress (13, 14). Body mass index (BMI) was obtained in all participants. We collected blood samples in fasting state defined as no caloric intake for at least 8 hours. Serum concentration of total cholesterol (T-Chol), high density lipoproteins (HDL) cholesterol, low density lipoproteins (LDL) cholesterol, triglicerides (TG), creatinine, thyroid-stimulating hormone (TSH) and high-sensitivity C-reactive protein (hsCRP) were measured using standard methods. The glycemic control was expressed by measuring HbA1c with the use of high-performance liquid chromatography (HPLC). The information on participants’ social and economic status, educational degree, lifestyle habits and diabetes-related issues was collected based on survey prepared for the purpose of this study. Chronic complications were assessed via medical chart review. We assumed the presence of microangiopathy when either retinopathy or nephropathy or neuropathy was diagnosed.

All participants provided written informed consent after reading the description of the study. The study was conducted in accordance with the Declaration of Helsinki and the protocol was approved by the local Ethics Committee.