Neuropahtic pain is defined by IASP as pain that occurs as a direct result of lesions or disease affecting somatosensory system. Diabetic Peripheral Neuropathy (DPN) is the most common complication of diabetes and may be found with and without neurophatic pain. It increases with duration of diabetes. There is also occurrence of depressive symptoms with persons with diabetes. Quality of life is a key parameter on which to base an objective assessment of the patient’s condition but also to predict the future course of the disease and the success of treatment. Objective The aim of this study was to examine whether Diabetic Peripheral Neuropathy and present depression significantly impact reduction in quality of life in diabetic patients. Subjects and Methods The study was conducted in Clinical Hospital Merkur- University Clinic "Vuk Vrhovac" Reference centre for health care of persons with diabetes of Croatian Ministry of Health and WHO collaborating institution. The study included 240 patients, 80 of which had been diagnosed with painful diabetic neuropathy (group B), 80 patients with diabetic neuropathy without pain (group D). The remaining 80 patients (control group K) were the patients who were treated in Clinical Hospital Merkur because of back pain and the diagnosis of DPN was excluded. In addition to a complete neurological examination included in the General Questionnaire on the Subject, demographic data was also collected. The EMNG tests of arms and legs were conducted, Doppler Ultrasound of leg artery, CDFI of carotid arteries and, when necessary, X-ray, CT or MRI test of lumbosacral spine. The quality of life of the subjects was questioned using the SF - 36 (Short Form Health Survey). For the assessment of symptoms and signs of neuropathic pain in patients two VAS (visual analogue scale) scales were used for current pain and pain during the past month and LANSS (Leeds Assessment of Neuropathic Symptoms and Signs) scale. Breakthrough of depression was tested by BDI-II (Beck Depression Inventory) survey. Results The average age of the subjects was 60.8 years (59.4 +/- 62.2 y). The study included 128 women and 112 men. Most of the subjects diagnosed with diabetes (group B and D) suffered from type II diabetes (87.4%). The average duration of disease was 18 years. Subjects with type I diabetes were significantly younger (49.5 years of age) than patients with type II diabetes (64.2 years of age). In subjects with type I diabetes the average duration of disease was longer (23.6 years) than in subjects with type II diabetes (17.2 years). Persons with diabetes without painful DPN suffered more often from type I diabetes compared to the subjects with painful DPN. As regards to the therapy they were taking, the majority of subjects (50.6%) were on insulin therapy, around one quarter of the subjects were either on a combination of peroral and insulin therapy (22.2%) or on a peroral therapy alone (27.2%). There were statistically significant differences of subjects by type of polyneuropathy according to the age, i.e. more severe forms were noticed in the older subjects. In 90.4% of subjects pain occurred couple of years before. In the past month, most of the subjects (47.1%) had pain every day, followed by those who had pain several times a week (33.8%) or several times a month. According to the parameter of the current intensity of pain, the highest figures were found in group B - 5.9 points VAS, and the lowest - 3.1 points VAS in Group D. The test of degree of pain during the previous month recorded similar results; the highest amount of 7.1 points VAS found in group B, and the lowest of 3.9 points VAS found in group D. By gender, women experienced pain significantly stronger than men. This applies both to current pain (4.8 versus 3.8 points), and pain during the previous month (6.5 versus 4.7 points). Current pain was significantly and linearly related to age, but not as regards to the pain during the past month. LANNS scale showed that the subjects of the study had an average of 12.2 points. According to Beck scale (revision II), the subjects got an average of 13.4 points. In both observed scales women showed on average statistically much higher figures of pain and depression than men. The stronger the pain that the subjects felt the stronger level of depression was found. It is interesting to note that the strongest correlation was found between the degree of pain during the past month according to the VAS scale. It can be concluded that the degree of pain determined in this manner is the best predictor of the level of depression in patients. The largest share of the subjects controlled defecation and urination (84.5%), while only a very small proportion of subjects controlled it partially or had not at all been able to control it. In women, the defecation and urination control was significantly weaker than in men. The same was found for sleep, whereas the women showed worse results. Accordingly, in group D, it was found that the highest number of subjects (85%) described their sleep as good, quite the opposite of group B with only 18.75% of subjects describing their sleep as good. The average number of medication, analgesics, was the highest in Group B (2.1), followed by the group K (1.7), while the lowest average number of persons taking medication was found in the subjects from the group D (1,2). By observing the results in all eight dimensions of the SF-36 scale, it is evident that the subjects from the general population had higher average results in all dimensions. On the basis of such comparison it is possible to conclude that the subjects of this study had on average lower quality of life than would be expected by observing the figures recorded in the general population. In all dimensions except for GH (general health perceptions), the lowest average figures were found in group B, and the highest in group D and the subjects from the Group K showed middle result figures compared to these two groups. It is also interesting to note that in four dimensions (VT, SF, RE and MH), the subjects of Group D showed higher average figures when compared to those found in the general population. The correlation of all 8 dimensions of the SF-36 scale with all three variables used to assess the degree of pain during the study with the results of the BDI scale was confirmed. It is evident that there is a strong negative linear correlation between intensity of pain and quality of life in all observed cases. The correlation was statistically significant for all dimensions of the SF-36, and for all three methods of pain evaluation, and the presence of depression symptoms. Conclusion The primary hypothesis - pain and depressive symptoms significantly impact the quality of life in patients with painful diabetic polyneuropathy was confirmed. The positive and statistically significant correlation between the two parameters, depression and pain, with all eight of the observed dimensions of quality of life of SF 36 survey lead to the conclusion that pain and depression caused a constantly lower quality of life in these patients.