Diabetes mellitus is a metabolic disease characterized by abnormal metabolism of carbohydrates, proteins and fat where the primary characteristic of the disease are elevated blood glucose levels. It occurs due to disturbances of insulin secretion from the pancreas, a change in its activity or both. Uncontrolled hyperglycemia is a cause of complications of a number of organ systems including eyes, nerves, kidneys and blood vessels. The most common oral manifestations are halitosis, destruction of the alveolar bone, xerostomia, Stomatopyrosis, inflamed oral mucosa prone to injuries, increased susceptibility to infections (candidiasis), increased risk of developing caries, periodontitis and increased exudation from gingival sulcus. For the purpose of proving the association between diabetes and hyposalivation, Pubmed was searched in the last 10 years with the keywords: diabetes, hyposalivation and xerostomia. Nine research studies were found that explored the interconnection of diabetes, hyposalivation and xerostomia. Varoius authors concluded that hyposalivation exists in people with diabetes and that there is a significant correlation between the degree of hyposalivation and glucose levels in saliva. Diabetes tends to decrease the pH of saliva, and thus a increases risk for caries development. Saliva substitutes can help reduce plaque index.