Diabetes Mellitus (DM) is a chronic metabolic disease that causes serious damage to the heart, blood vessels, eyes, kidneys and nerves. Both the number of cases and the prevalence of diabetes have been increased rapidly over the past 30 years. According to the report of the International Diabetes Federation (IDF) Report, approximately 537 million people worldwide (700 million in 4045) have diabetes and 6.5 million people were reported to have died due to diabetes in 2021. In Turkey, it is estimated that approximately 9 million people (about 13.5 million in 2045) are diagnosed with diabetes and approximately 80 thousand people will die from diabetes.

Prolonged hyperglycemia in DM can lead to microvascular (nephropathy, retinopathy and neuropathy) and macrovascular (peripheral vascular disease, hypertension, cerebrovascular disease, ischaemic heart disease) complications. However, due to poorly controlled DM, complications can be seen in the oral mucosa of patients with many immunological and metabolic changes. Oral complications seen in patients with DM include hyposalivation, xerostomia, bacterial, viral and fungal infections, poor wound healing, increased severity and incidence of caries, gingivitis and periodontal disease, periapical abscess, and burning mouth syndrome (BMS). These complications can lead to the development of oral mucositis in patients.

Many pharmacological and non-pharmacological agents are used in the prevention/treatment of oral mucositis. According to the classification of the National Center for Complementary and Integrative Health (NCCAM), complementary therapies methods are divided into three groups as nutritional, psychological and physiological and other complementary approaches. However, it is reported in the literature that complementary therapies such as cryotherapy (oral cooling), honey, propolis, vitamin E, selenium, aloe vera, black mulberry, apple cider vinegar, rose water and green tea are effective in the treatment of oral mucositis. Again in the literature, there are studies in which the effect of black mulberry syrup in patients with Chronic Obstructive Pulmonary Disease (COPD), apple cider vinegar and rose water mixture in cancer patients and green tea in the treatment of oral mucositis has been proven.

Oral mucositis is one of the oral diseases that can cause oral dysfunction, dysphagia and reduced oral health-related quality of life in patients. Oral and dental health affects a person's quality of life by affecting their physiological, psychological and social functioning. However, improving oral health is part of nursing care. In order to maintain a good quality of life, it is necessary to improve awareness of oral complications that occur in patients with DM. In the literature reviewed, only one experimental study was found in cancer patients in which oral mucositis-related quality of life was evaluated. There is no international or Turkish study on the treatment of oral mucositis in patients with DM. There are also no studies comparing hawthorn vinegar, black mulberry syrup and green tea in different sample groups. In this context, this study investigated the quality of life related to oral mucositis and oral health in patients with DM using hawthorn vinegar, black mulberry syrup and green tea.