Everyone has heard about insulin but, what does this hormone really do? Insulin is not just a treatment for those with diabetes; it's an essential player in the body’s energy management system. In this post, we'll delve into the pivotal role of insulin in metabolism and the potential fallout when blood sugar is left unattended.
When people eat, the digestive system breaks down complex sugars from foods rich in carbohydrates (bread, potatoes, fruit, etc) into smaller ones, primarily glucose. Glucose, together with proteins and lipids, are the main energy sources for cells to function properly [1] - to ensure we function properly. Insulin then gets released by the pancreas, allowing glucose to enter cells and control its amount in the bloodstream [2].
When excess food is consumed and cells have enough glucose to work, insulin stores the extra glucose in two different parts, ensuring the first storage is full before going to the next [2];
Converts it to glycogen (a molecule formed by many connected glucose molecules) in the liver and muscle cells.
Lipids in fat cells (the adipose tissue).
Insulin also helps the absorption of amino acids to be used for protein production in the cells (protein metabolism) [2].
Figure 1. Insulin allows glucose in the bloodstream to enter the cells. Glucose will then be used to produce energy or stored as glycogen and lipids for later use. Insulin also helps with the absorption of amino acids.
Following the previous order, when food is scarce, the body uses up glycogen (which is re-converted to glucose), then lipids, then proteins to obtain the necessary energy to continue living until it can eat more food. This process is done by another hormone called glucagon [3]. Although less known than insulin, this hormone is very important for survival to increase glucose levels in the bloodstream to be used by the cells.
Figure 2. Glucagon works in opposition to insulin by raising blood glucose levels when they are too low. During prolonged fasting, it promotes energy production from lipids and amino acids.
When blood sugar regulation is impaired, glucose levels rise - a condition known as hyperglycemia. Although this is most commonly due to uncontrolled diabetes, it can also be caused by certain medications, excess stress or growth hormone, and damage to the pancreas among others [4] Hyperglycemia can have severe consequences on the body if left untreated, including [4-6]:
Weight Loss: the body may break down muscle and fat for energy when it cannot utilize glucose effectively, leading to unexplained weight loss.
Fatigue: constant fatigue and a lack of energy, as the body's cells may not be receiving the necessary fuel.
Damage to Blood Vessels: over time the damage increases the risk of atherosclerosis (hardening and narrowing of arteries) and subsequent cardiovascular issues such as heart disease and stroke.
Kidney Damage: the kidneys play a crucial role in filtering waste products from the blood. Having too much glucose in the tiny blood vessels in the kidneys can damage them, leading to impaired kidney function.
Eye Problems: damage to the small blood vessels in the eyes leads to conditions like diabetic retinopathy. This can result in vision problems, including blindness if left untreated.
Weakened Immune System: individuals are more susceptible to infections and healing wounds slower than usual.
Nerve Damage: this can result in symptoms like numbness, tingling, and pain, primarily affecting the extremities.
Skin Issues: hyperglycemia can exacerbate conditions such as bacterial and fungal skin infections. Collectively with the weakened immune system and the nerve damage (not feeling pain), this may result in amputation as sometimes people do not realize the damage until it is too late.
In conclusion, insulin is an essential hormone in the metabolism process, and a malfunction in the production or work of this hormone has several consequences. In this case, cells cannot obtain the necessary glucose to function and glucose levels will stay high – most commonly due to diabetes. Stay tuned for next week’s post where we will delve deeper into this condition that affects millions of people worldwide!
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Written by: María
Edited by: Natasha
Figure created by: María
BioDecoded is a volunteer group committed to sharing accurate scientific information. We cannot offer any specific health advice. If you have any questions about this topic or would like to learn more, please comment below, or send us your questions.
References:
What is Glucose? (2022). Web MD. Available at: https://www.webmd.com/diabetes/glucose-diabetes (Accessed: 19 November 2023).
Vargas, E., et al. (2022). Biochemistry, Insulin Metabolic Effects. StatPearls. Available at: https://www.ncbi.nlm.nih.gov/books/NBK525983/
Rix, I., et al. (2019). Glucagon Physiology. Endotext. Available at: https://www.ncbi.nlm.nih.gov/books/NBK279127/
Hyperglycemia (2023). Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/diseases/9815-hyperglycemia-high-blood-sugar (Accessed: 19 November 2023).
Dangers of Uncontrolled Blood Sugar (2023). Available at: https://my.clevelandclinic.org/health/diseases/9815-hyperglycemia-high-blood-sugar (Accessed: 19 November 2023).
Hyperglycemia in Diabetes (2023). Mayo Clinic. Available at: https://www.mayoclinic.org/diseases-conditions/hyperglycemia/symptoms-causes/syc-20373631 (Accessed: 19 November 2023).
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