Objective: To relate different oral manifestations and oral complications of diabetes mellitus Background: Diabetes mellitus is a chronic lifestyle disease affecting all age groups. It is one of the leading causes of mortality and morbidity worldwide. The term "diabetes mellitus" describes a group of disorders characterised by elevated levels of glucose in the blood and abnormalities of carbohydrate, fat and protein metabolism. A number of oral diseases and disorders have been associated with diabetes mellitus, and periodontitis has been identified as a possible risk factor for poor metabolic control in subjects with diabetes. The article will speak in depth about the complications of diabetes mellitus. This article aims to review and increase the awareness of oral manifestations and complications of diabetes mellitus and to stimulate research on the subject. Reason: It is important to know the different oral manifestations of diabetes mellitus to prevent its complications at the early stages.
INTRODUCTIONDiabetes mellitus is a growing public health concern and a common chronic metabolic disease worldwide [1][2][3][4] . Diabetes mellitus represents a group of metabolic diseases that are characterised by hyperglycaemia due to a total or relative lack of insulin secretion and insulin resistance or both. The metabolic abnormalities involve carbohydrate, protein and fat metabolism. Diabetes mellitus affects all age groups, but is more common in adults. The World Health Organization (WHO) has recently declared it to be a pandemic 2 . Its prevalence has increased dramatically over the past few decades and it is expected to triple in the next decade. Diabetes mellitus is considered a leading cause of death due to its microvascular and macrovascular complications 5,6 . The most common types of diabetes are type 1 (insulin dependent) and type 2 (non-insulin-dependent) 7,8 . Type 2 is the more prevalent type. Countries with the highest rates of diabetes in the Eastern Mediterranean region and the Middle East are the United Arab Emirates, Saudi Arabia, Bahrain, Kuwait and Oman
9. Oman is one of the countries that has a high prevalence of diabetes mellitus, especially type 2 diabetes, and its prevalence is expected to increase in the next twenty years 10,11 .Various inflammatory diseases and soft tissue pathologies in oral cavities are associated with diabetes mellitus [12][13][14] . However, awareness of these complications is lacking worldwide [15][16][17][18] . Periodontal diseases have been proposed as the sixth most prevalent complication of diabetes mellitus following the other diabetic complications 19 . It has been reported as a more frequent oral complication of diabetes compared to other oral manifestations such as dry mouth and caries. Periodontitis is more frequent and severe in patients with diabetes with poor glycaemic control. Early identification and/or management of these oral manifestations may help in the early diagnosis of diabetes and in attaining better glycaemic control 20 . Therefore, diabetic oral c...