The investigation of serum and saliva endostati̇n, endocan levels in patients with type 2 diabetes mellitus

Diabetes mellitus is a chronic metabolic disease characterized by hyperglycemia that causes disruptions in carbohydrate, protein and fat metabolism as a result of the defect of insulin secretion and/or tissue response to the hormonal effect of insulin. Type 2 DM is characterized by impaired insulin secretion, insulin resistance, increased hepatic glucose production, and abnormal fat metabolism. Insulin resistance is the deterioration of the biological response to insulin in muscle, adipose tissue and liver, which are the target tissues of insulin. There are many genetic and environmental factors in the etiology of Type 2 DM. Many hormones and peptide molecules, especially insulin and glucagon, play a role in the regulation of blood glucose level. Endostatin, First isolated from mouse hemangioendothelioma cells by O'Reilly et al, endostatin is a 20-kDa molecular weight component derived from the carboxy terminus of Collagen type XVIII. It prevents proliferation and migration of endothelial cells. Collagen type XVIII is found extensively in basement membranes, extracellular matrix, and especially in the liver. It is thought to play a role in many chronic diseases and metabolic diseases such as diabetes. Endocan is a 50 kDa dermatansulfate proteoglycan synthesized and secreted from active vascular endothelial cells, measurable in serum. The endocan molecule was first discovered by Lassalle et al. in 1996. This molecule, known as endothelial cell specific molecule-1 (ESM-1) before 2001, was named endocan after 2001. Endocan, which was initially thought to be associated only with vascular endothelial cells, was also found in skin microvascular tissue, pulmonary arteries and coronary arteries in later studies. Since diabetes is a cause of vascular damage, its relationship with diabetes is a molecule under investigation. A total of 100 participants were included in the study, with 80 patients divided into four groups based on HbA1c [Group 1: 5.7-6.4 % (n=20), Group 2: 6.5-8.4 % (n=20), Group 3: 8.5-9.9 % (n=20), and Group 4: 10 % and above (n=20)] and a control group of 20 healthy individuals. After at least 8 hours of fasting, venous serum and saliva samples were obtained from the patient and control groups. In venous serum, the levels of fasting blood glucose, low-density lipoprotein, aspartate aminotransferase, alanine aminotransferase, sodium, potassium, creatinine, and HbA1c were measured. The levels of endostatin, endocan in serum and saliva were determined by using the enzyme-linked immunosorbent assay (ELISA). The statistical analyses were performed with the SPSS 22 package program and also one-way Anova test and Pearson's correlation test were used. The significance value was taken as p≤ 0.05. When the endocan blood concentration was examined, we found that there was a positive correlation between endocan saliva and a negative correlation between HbA1c and FBG. When the endostatin blood concentration was examined, we found that there was a positive correlation between endostatin saliva and HbA1c, and there was no statistical difference between HbA1c and FBG. As a result, both blood and saliva levels of endocan and endostatin were correlated with each other. This made us think that these two peptides are found in saliva and may be secreted by the salivary glands. It shows that saliva values can be used instead of blood in future studies with these molecules. This may be preferred over blood sampling, which is an invasive procedure. In our study, we found a negative correlation between endocan blood and saliva concentrations in diabetic patients. We could not find a relationship between endostatin values and prediabetes or diabetes patients. We think that more long-term studies with more parameters are needed to investigate the role of endostatin and endocan in diabetes. Key words: Diabetes mellitus, Peptide molecules, Endostatin, Endocan, HbA1c