Study of Association of Salivary Adipokines With Prediabetes and Type 2 Diabetes Mellitus

This study is conducted in a tertiary care hospital, Dr.A.Ramachandran's Diabetes Hospitals, Chennai. The persons with no history of diabetes, seeking a screening for diabetes will be invited to participate in the study and after signing the informed consent form they will be assessed by the risk score. The patients who fulfill the inclusion criteria will be enrolled in this study and additional tests will be done. We will also invite the patient's spouse, relatives or friends who are willing to participant in this study.

Preliminary screening: The team comprises of one research associate (dentist), one research associate, two laboratory technicians and one lab assistant. The measurements will be assessed by the same members of the team throughout screening, to eliminate potential inter-observer variation. Participants aged ≥35 years who visit the clinic will be invited to undergo a preliminary screening. Weight and height are measured with the participants wearing light clothes without shoes. BMI is calculated (kg/m2). Waist circumference is measured midway between the lower rib margin and the iliac crest. Blood pressure is measured using a standard mercury sphygmomanometer after a 5-minute rest. An average of the two readings is used for the analysis. Previous history of hypertension, borderline diabetes and gestational diabetes will be ascertained. Family history of diabetes, heart disease, stroke and sedentary life style are recorded in a structured questionnaire. If the participant has 2 or more risk factors they will be tested for fasting and 2h plasma glucose after 75gm of Oral Glucose (Accu check performa, Roche Diagnostics).

Next day participants will be categorized based on the inclusion and exclusion criteria as Normoglycemic, Pre diabetic (IFG/IGT) and newly diagnosed Type 2 diabetic patients. The selected participants will undergo dental examination to check for periodontitis. Then salivary and fasting serum sample is obtained from all the individuals for estimation of biomarkers (adiponectin, apelin, visfatin and vaspin). HbA1c, Lipid profile and Gamma-glutamyl transferase (GGT) is analysed in fasting serum.

Approximately 10 ml blood is collected in a serum tube. Blood sample separation is performed at the central investigational laboratory. Blood samples are separated, aliquoted, refrigerated and immediately stored at -70˚C for biomarker analysis. HbA1c is measured by immunoturbidometry (tina-quant II; roche diagnostics corporation, germany); a procedure certified by the national glycohemoglobin standardization programme. The fasting serum lipid profile (total cholesterol, triglycerides and high density lipoprotein, cholesterol) and GGT is estimated using standard enzymatic methods. Biochemical assays are performed on a Cobas Integra 450 plus (Roche, Germany) autoanalyzer using reagents from Roche diagnostics, with appropriate quality control methods (Roche diagnostics reference serum).

Unstimulated salivary samples will be collected in a sample collection tube. Participant will be asked to refrain from eating or drinking for about two hours prior to saliva collection; it is done around 8am - 10am. Subjects will be asked to rinse their mouth with drinking water and then to expectorate whole saliva in a collection tube. The saliva is then centrifuged at 9300g at 40 C for about 10 minutes and then stored at -70 degree C, until further use.

Saliva and plasma will be thawed at room temperature for biomarkers measurement by enzyme-linked immunosorbent assay (ELISA). A commercial ELISA kit for human biomarkers for serum and saliva is used and the assay is conducted according to the manufacturer's instructions. Each sample of saliva and plasma from the same patient will be analysed in the same experimental set. Plasma samples require dilution. Saliva samples will be analyzed without dilution.

Reports will be dispatched from the central laboratory to the participants by courier. Participants with newly diagnosed diabetes or uncontrolled diabetes will be referred to a diabetologist for treatment and followed up for two year. Individuals with prediabetes will be advised to improve physical activity and dietary habits and followed up for two year. Participants with periodontitis will be referred to a dental surgeon and followed up for two year.

During visit 4 \& 6 the participant's weight, waist circumference, BMI, blood pressure will be measured and laboratory investigations like Fasting and 2hr postprandial blood glucose, HbA1c and Lipid profile. At Visit 6 the participant's saliva and serum samples are collected for adipokines measurement.