A Question of Physiology: Is insulin a polypeptide hormone? 

Is insulin a polypeptide hormone? In order to determine the answer, we must first understand what insulin is. One in ten adults worldwide has diabetes. This disease has raised much concern and discussion. When it comes to diabetes, insulin as an effective treatment has been always mentioned and needs to be highlighted. 

What is insulin?

Insulin is a polypeptide hormone that plays a major role in regulating blood sugar levels inside the living body. Insulin is synthesized and secreted by pancreatic beta cells. It consists of 51 amino acids and has a molecular weight of approximately 5808 Daltons. The structure of insulin is composed of an A chain, a B chain, and a C chain, linked together by disulfide bonds. The A chain has 21 amino acids, the B chain has 30 amino acids, and the C chain has only one amino acid. Therefore, we can now answer the question in the title with a big "Yes".

What is polypeptide hormone?

Polypeptide hormones refer to a group of hormonal molecules composed of amino acids that perform regulatory roles in living organisms. Mostly, polypeptide hormones are molecules made up of two or more amino acid residues linked by peptide bonds, and their structures include short, medium, and long peptides. Now you might wonder: Is insulin a polypeptide hormone that has the same structure as what was explained above? The answer is still yes.

Peptide hormones are commonly secreted through endocrine glands such as the pancreas, pituitary gland, and thyroid gland. These glands contain secretory cells which, when suitably stimulated, will release peptide hormones into the circulatory system. The family of polypeptide hormones includes growth hormone analogs, corticotropin, gonadotropin, insulin and its analogs, insulin-like growth factor, and parathyroid hormone. Among all these hormones, insulin is just one kind of polypeptide hormone.

What is the main function of insulin?

Is insulin a polypeptide hormone that maintains the balance of the body like other hormones? When blood glucose concentration rises, pancreatic beta cells will release insulin into the bloodstream. By binding to insulin receptors on cell membranes, it promotes the uptake and utilization of glucose by the cells, thereby lowering blood glucose levels. 

Meanwhile, insulin also promotes glycogen synthesis in the liver and muscle tissue as a means of inhibiting glucose production, as well as promoting the synthesis and storage of fat cells. Because of its unique function, insulin is widely used in the treatment of diseases such as diabetes. It is supplemented by means such as injections or insulin pumps to help control blood sugar levels.

What is the normal state of insulin in the human body and how to maintain it?

The normal state of insulin levels is 29-172 mu/L for adults, 42-243 mu/L for the elderly, and 10-20mu/L when empty. When it is higher than normal, it could cause obesity, hypoglycemia, edema, and other related problems. When it is lower than normal, it could cause ketoacidosis, raise blood sugar, and trigger diabetes.

So, how can you keep insulin levels in balance? Insulin, like other polypeptide hormones, is strongly linked to people’s diet. It is easy to understand that following a healthy and regular diet helps a lot, while there are more things that could be done to help. Here are some tips:

1.Make sure you get good sleep. Research indicates that sleep deprivation triggers a stress response that results in an excess production of glycemic hormones, ultimately elevating blood sugar levels.

2.Enjoy sun exposure. Moderate sun exposure will benefit insulin secretion. According to studies, spending time in the sun encourages the skin to release nitric oxide, which improves metabolism and cardiovascular health.

3.Avoid negative emotions and be relaxed. The presence of negative emotions and mental stress can trigger the release of adrenaline and other hormones that raise glucose levels, resulting in an elevation of blood glucose and blood pressure. Clinical research shows that excessive worry about slight fluctuations in blood glucose levels can hinder effective blood glucose control and the recovery of pancreatic islet function.

Conclusion

Insulin is classified as a polypeptide hormone, but it is not synonymous with all polypeptide hormones. “Polypeptide hormone” is not a single substance that refers to just one hormone, but a collection of hormones that help maintain a healthy equilibrium within our bodies. Insulin is a member of this group, but its specific role is to regulate blood sugar levels. In conclusion, we can say that insulin is a polypeptide hormone, but not all polypeptide hormones are insulin.