Salivary Insulin

Intended Use

The Salimetrics® Insulin ELISA Kit is an indirect sandwich ELISA specifically designed and validated for the quantitative measurement of salivary Insulin. It is not intended for diagnostic use. It is intended only for research use in humans and some animals. Salimetrics has not validated this kit for serum or plasma samples.

Introduction

Insulin, a critical peptide hormone produced by the pancreatic β-cells, regulates glucose homeostasis and energy metabolism by facilitating the uptake of glucose into cells and influencing carbohydrate, protein and lipid metabolism, as well as cell division and growth. The lack of Insulin production in Type I Diabetes Mellitus, caused by autoimmune islet destruction, results in pathogenic levels of glucose in the blood and requires exogeneous Insulin administration. Type II Diabetes Mellitus is caused by the lack of Insulin activity referred to as Insulin Resistance. Elevated fasting Insulin levels and/or the dysregulation of Insulin after ingestion of glucose over time are diagnostic hallmarks of Insulin resistance. In many cases, people are unaware of their pre-diabetic state since Insulin resistance can occur prior before systemic glucose levels become problematically high. Fortunately, Insulin Resistance is reversible by behavioral health changes which present an important opportunity for a pre-diabetic individual to avoid Type II Diabetes altogether.

Traditionally measured in serum, advancements now allow for the assessment of Insulin levels in saliva, providing a non-invasive, simpler alternative for research involving frequent sampling. In saliva, Insulin shares a nearly linear correlation to fasting blood levels (r = 0.92) and is a reliable surrogate for serum measurements as shown in the figure below. The detection of salivary Insulin has a crucial temporal aspect; there is an approximate 40-minute delay in salivary Insulin response compared to serum after a glucose challenge. Saliva collection reduces patient discomfort, risk of infection, and the need for specialized medical staff, making it particularly beneficial for vulnerable groups and suitable for large-scale studies or fieldwork. One significant benefit of measuring Insulin in saliva is the ability to easily and painlessly collect multiple samples after a glucose challenge, facilitating post-prandial studies without the need for repeated blood draws. These advantages seems to be particularly helpful for studies of childhood obesity or gestational diabetes in pregnant women.

Insulin Assay Principle

This is an indirect sandwich ELISA kit. A “sandwich” is formed when both a capture anti-Insulin antibody and a detection anti-Insulin antibody bind Insulin. The detection antibody is directly linked to horseradish peroxidase. After incubation, unbound components are washed away. Bound anti-Insulin detection antibody is measured by the reaction of the horseradish peroxidase enzyme to the substrate tetramethylbenzidine (TMB). This reaction produces a blue color. A yellow color is formed after stopping the reaction with an acidic solution. The optical density is read on a standard plate reader at 450 nm. The amount of anti-Insulin detection antibody is directly proportional to the amount of Insulin present in the sample.