The investigation of serum and saliva phoenixin levels in patients with TYPE 2 diabetes mellitus

Diabetes is one of the most common metabolic diseases in the world. It is a chronic condition caused by insulin resistance or insufficient insulin production. Many peptide hormones have a role in its etiology. Phoenixin (PNX), a recently discovered neuropeptide, was reported to be present in rat pancreatic islets. PNX appears to have a role in energy management and metabolism through regulating insulin neogenesis and secretion, according to research. Polycystic ovarian syndrome, anorexia nervosa, and nonalcoholic fatty liver disease have all been associated with PNX. However, no research has been done on the association between diabetes and PNX levels. The aim of the study was to see if there was a link between PNX levels in the serum and saliva of patients with diabetes and HbA1c levels. 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 (FGG), low-density lipoprotein, aspartate aminotransferase, alanine aminotransferase, sodium, potassium, creatinine, and HbA1c were measured. The levels of phoenixin 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 PNX serum levels were analyzed, it was shown that the prediabetic group (Group 1 (5.7-6.4 %)) had statistically higher levels than type 2 diabetes mellitus patients (p≤0.05). PNX salivary levels were found to be significantly higher than serum levels in the control and type 2 diabetes mellitus groups. Eventually, the PNX molecule is a neuropeptide that may be found in saliva and serum. It has been shown that the amount of PNX in the serum of prediabetic people is higher than that of patients with type 2 diabetes. It's thought that the prediabetic groups' higher serum PNX level is attributable to the effect of hyperinsulinemia, and that when overt diabetes occurs, it will be detected at a lower level in the serum related to relative insulin insufficiency. This leads us to believe that PNX is increased in order to control the higher glucose levels in the prediabetic group. The salivary glands are thought to be one of the sources of PNX present in saliva. The salivary gland is one of the synthesis and secretion locations, hence it is predicted to be higher than the serum level. Saliva PNX is expected to be favoured over serum PNX in future investigations on PNX metabolic pathways, as serum PNX is an invasive procedure. Key words: Diabetes mellitus, peptide molecules, phoenixin, Hb1Ac