Science of Insulin: Functions, Metabolism, and Diagnostic ELISA Applications

Insulin is regarded as a critical hormone within the human body, it main action is as a primary regulator during the process of energy metabolism and controlling levels of blood glucose. It is predominately produced by beta cells that are found in the pancreatic islets.  Insulin functions by ensuring that all cells receive sufficient fuel so that they can ensure that the systemic balance is maintained. Therefore, it is vital to understand the function of insulin and be able to measure its levels accurately, this is paramount for managing various metabolic disorders which are associated to insulin such as diabetes and polycystic ovary syndrome (PCOS).

Physiological role in glucose homeostasis

A primary function of insulin is in facilitating the uptake of glucose into cells.  This occurs mainly in skeletal muscle and adipose tissue. When we consume foods that are rich in carbohydrates, this causes our blood glucose levels to increase, this leads to a signal being sent the pancreas which causes it to release insulin into the bloodstream. Insulin carries out its function by binding to specific receptors that are found on the surface of cells, once bound activates the glucose transporter proteins (GLUT4).

In addition to glucose transport, other vital roles of insulin include lipid and protein metabolism. It is instrumental in the promotion of lipogenesis (which is the storage of fat) and in the inhibition lipolysis (which is the breakdown of fat), it can also stimulate the uptake of amino acids and protein synthesis. During periods when the production of insulin is not enough or in some cases when the body is resistant to the effects of insulin, glucose is found to remain in in the bloodstream, this can lead to hyperglycemia and other long-term complications which are linked with diabetes.

Measuring insulin levels

In both clinical and laboratory research settings, the accurate measurement of the levels of insulin is required for the accurate diagnosis of insulin resistance and or in the monitoring of therapeutic interventions. The Enzyme-Linked Immunosorbent Assay (ELISA) is seen as the gold standard in the detection of insulin levels; this is because of the high sensitivity and specificity that this procedure offers.

An insulin ELISA kit is often used to detect the amount of insulin that is present samples such as serum, plasma, and cell culture supernatants. ELISA assays are based on a “sandwich” technique, where two specific antibodies are designed to interact and bind to the insulin molecule. This method can allow scientific researchers to distinguish between the presence of endogenous insulin, and many other similar molecules present with a given sample. This then provides a much clearer picture of how well the pancreatic beta-cells are functioning with the body. This kind of precision is essential so that a personalised medical treatment becomes the standard way for detecting and treating many different types of metabolic syndromes.

C-Peptide is a good indicator of the production of endogenous insulin

When the body produces insulin, it is initially synthesised as a precursor protein that is called proinsulin. This proinsulin is first cleaved into two separate parts: one of the molecules becomes insulin and the other becomes c-peptide. Since c-peptide and insulin are both released into the bloodstream and released in equal amounts, and that the half-life of c-peptide is greater, c-peptide serves as a much stable marker to use detect levels of insulin that are naturally being produced by the body.

However, need to distinguish between the amount of insulin produced by the body and the amount of exogenous insulin injected in patients experiencing hypoglycemia is critical or during evaluation of Type 1 diabetes progress.

Researchers can also use the c-peptide ELISA kit to make assessment of the residual beta-cell function. In cases where high levels of c-peptide are a good indication of insulin resistance or even Type 2 diabetes, whilst presence of low levels can be characterised by Type 1 diabetes or even Type 2 diabetes at a later-stage where the exhaustion of the pancreas has occurred.

Glucagon is regarded as the counter-regulatory balance of insulin

Insulin does not function on its own, glucagon is the primary antagonist and has an important role in counter-regulatory balance the levels of insulin present.

While insulin is known to lower the levels blood glucose mainly through promoting storage, glucagon on the other hand is secreted by the alpha cells present within the pancreas and this cause blood glucose to increase by stimulating the liver to release stored glycogen so that this can be converted to glucose. This antagonist relationship regulates the blood sugar levels and ensures that it remains within a narrow, healthy range, even in conditions during fasting or even intense exercise.

In several metabolic diseases it has been found that this balance has been disrupted. One example is in patients with Type 2 diabetes, in this instance many patients will suffer from hyperglucagonemia, a condition where the body produces too much glucagon even when blood sugar is high. To study this complex interplay, scientist can use a glucagon ELISA kit to monitor the levels present. In carrying out the measurement glucagon alongside that of insulin, clinicians will be able to gain a more comprehensive understanding of the patient’s glycemic control and then be able to provide tailor treatments that will be targeting both hormones at the same time.

Conclusion

The global burden is greater than ever as the number of different metabolic disease continues to grow. This makes studying molecules such as insulin and many related hormones more vital than ever. To understand the basic physiological mechanisms of glucose uptake, the use of highly precise diagnostic ELISA kits is fundamental in ability of scientist to monitor correctly and to manipulate these pathways becomes key to improving patient outcomes. This could be either by detecting insulin directly or by evaluating levels of its counterparts such as c-peptide and glucagon. These essential tools provide the data which is essential in our battle against the rising tide of diabetes and various other metabolic syndromes.