Insulin: Major Causes Of Resistance And Why

Insulin is a hormone produced by the pancreas that allows cells to absorb glucose, which is the body's preferred source of fuel. Insulin resistance occurs when cells do not properly absorb glucose, resulting in a buildup in the blood. If left untreated, insulin resistance may lead to prediabetes, a condition in which glucose levels are higher than normal but not high enough to be considered diabetes. Here are some possible reasons why individuals with insulin resistance are not able to effectively use insulin.

How Resistance Develops

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Insulin resistance may occur as a result of many risk factors, some of which are due to lifestyle habits and can be changed to prevent prediabetes. Other factors such as biochemical or genetic reasons are not as easy to change. A persistently high level of insulin over an extended period causes a decrease in the body's sensitivity to insulin, which results in insulin resistance. When cells are not able to absorb glucose, their primary source of energy, it causes an increased risk of many health problems.

Infections

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According to a 2006 study, healthy middle-aged men with recent infections, especially enteroviruses and chlamydia pneumonia, had an increased risk of insulin resistance. Although the link between infections and insulin resistance is not entirely known, researchers believe it may have something to do with the inflammation caused by an infection. According to Doctor Mario Kratz of the Fred Hutchinson Cancer Research Center in Seattle, who has been studying the link between diabetes and inflammation for years, it seems pretty clear that inflammation plays a significant role in the development of insulin resistance.

Obesity

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A diet high in refined carbohydrates, processed foods, and sugar may lead to obesity, which is widely associated with an increased risk of insulin resistance. According to a 2012 study, prolonged exposure to a high amount of fatty acids may lead to insulin resistance. Saturated fatty acids, such as stearic and palmitic acids, were found to the most potent cause of insulin resistance. The study went on to state fatty acids impair insulin actions by creating oxidative stress, modulating gene transcription, and causing mitochondrial dysfunction and inflammation.

Refined Carbohydrates

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Research shows processed or refined carbohydrates including sugary cereals, pasta, white rice, bread, and artificial sweeteners have been linked to weight gain, increased fatty acids in the liver, overeating and increased appetite, metabolic syndrome, systemic inflammation, high blood sugar, insulin resistance, and diabetes. A 2014 study found a higher consumption of refined grains such as white rice increases the risk of type two diabetes. The study stated a high consumption of rice and noodles might contribute to hyperglycemia due to greater insulin resistance. Healthy carbohydrates to focus on instead are fruits and vegetables.

Inactivity

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Exercise is one of the best ways to eliminate insulin resistance because exercise stimulates muscle tissue to burn fat. Exercise also allows muscle groups to absorb glucose from the blood without the help of insulin. A 2008 study found even a short bout of exercise increases an individual's glucose uptake through a mechanism that bypasses normal insulin signaling defects. The downside is these effects wear off after forty-eight hours; therefore, exercise needs to be done consistently to be effective. Most experts state getting at least thirty minutes of moderate to intense exercise five times a week is sufficient to maintain a healthy body.

Vitamin D Deficiency

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In the past, low vitamin D levels in the blood have been linked to obesity, but recent research shows vitamin D may also play a role in diabetes and, thus, insulin resistance. One study showed regardless of weight, individuals with low vitamin D levels were at an increased risk of developing metabolic syndrome, prediabetes, and type two diabetes, which can all play some role in how the patient's body deals with insulin. Another study showed the progression of diabetes in pre-diabetic individuals went down by eight percent for every unit increase in vitamin D levels. Eating a healthy diet and getting plenty of exercise outdoors is a good way to increase vitamin D levels.

Sleep Apnea

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Sleep apnea is a chronic condition characterized by the constant collapsing of the patient's upper airway while they sleep, which causes the affected individual to keep waking up throughout the night as they are unable to breathe properly. This condition is most common in middle-aged obese men. According to a 2007 study, sleep apnea is associated with an increased risk of hyperleptinemia, which may lead to insulin resistance. One study even found an association between non-obese individuals with sleep apnea and insulin resistance. The good news is, there are a few methods of treating sleep apnea available, including the most well-known: continuous positive airway pressure (CPAP) machines.

Pregnancy

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An increase in the hormone progesterone and others may boost insulin resistance during pregnancy even in women who do not have preexisting diabetes or insulin disorders. Gestational diabetes occurs when pregnant women develop high blood sugar even though they have never had diabetes before. A pregnant woman may need up to three times the amount of insulin as she normally does to feed her growing baby. Insulin resistance may occur as a result of an increase in hormones in the body, which makes it harder for the expectant mother to use insulin.

Cigarette Smoking

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Smoking cigarettes may increase the likelihood of developing type two diabetes by up to forty percent, according to the Centers for Disease Control and Prevention. Individuals who smoke are also more likely than nonsmokers to have trouble with insulin dosing and controlling their disease. The Centers for Disease Control also stated the more cigarettes a person smokes, the higher their risk of developing type two diabetes, heart disease, and kidney disease is. With this in mind, it is incredibly beneficial for individuals to reduce their smoking habit, or even quit entirely. Not only can this prevent insulin resistance, but it can also reduce the individual's risk of countless other health issues as well.

Inflammation

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Insulin resistance may be due to chronic inflammation in the body. Research shows the immune system releases inflammatory mediators known as cytokines in individuals dealing with prediabetes and type two diabetes, which seem to disturb the mechanisms of insulin. Damage from free radicals and oxidative stress causes inflammation that has been linked to an individual's development of insulin resistance. 

Inflammation is largely in part due to high levels of stress, not enough sleep, poor exercise habits, and a diet high in inflammatory foods. thus, individuals should look at engaging in effective stress management, regular exercise, and transitioning to consuming mostly anti-inflammatory foods to reduce the potential of insulin resistance and other health concerns.

Chronic Stress

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Chronic stress is often a trigger for the development of insulin resistance. When an individual is under mental, physical, or emotional stress, the body responds by releasing stress hormones called adrenaline, norepinephrine, and cortisol. These stress hormones are released to prepare the body for a fight or flight response, increasing the demand on the body for energy. In order for the muscle cells to get this energy, a hormone called insulin has to be able to transfer glucose to the muscle cells. Some individuals produce insulin that does not perform this function well. 

Insulin resistance occurs when the cells do not necessitate the glucose or extra energy that floods into the individual's bloodstream every time stress hormones are released. This process means chronic stress causes glucose to build up in the blood, forcing the body to produce excessive amounts of insulin in response. As the cells become more resistant to the high levels of insulin, the pancreas becomes too tired out to modulate high blood sugar levels. Consistently elevated blood sugar causes the development of type 2 diabetes.

Metabolic Syndrome

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Metabolic syndrome is the umbrella term used to characterize a group of conditions that include excess body fat around the waist, high blood pressure, abnormal cholesterol levels, and high blood sugar. When an individual has more than one of these conditions, they have metabolic syndrome. The same mechanisms that cause metabolic syndrome are what causes insulin resistance to develop. When an individual consumes food, the fat and glucose from the food are metabolized and used to make cellular energy, or it is stored if it is not needed. When an individual consumes more calories than their body is burning, the excess fat and glucose are stored in the blood and body tissues. 

Over time this causes excess body fat, high blood pressure, and abnormal cholesterol levels. Some extra glucose remains in the blood because the body unable metabolize it for storage as quickly as the individual is consuming it. This glucose in the blood causes high blood sugar levels. If the insulin the individual's body produces is not productive at transferring the extra glucose to the muscle cells, it continues to build up in the blood, and the body tries to compensate by making more insulin. Eventually, the cells become so used to high insulin that they no longer respond to it. The inadequate response of the body to the insulin is what characterizes insulin resistance.

Certain Medications

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Certain medications can have an influence on an individual's development of insulin resistance. All medications have side effects, but particular medications have the side effect of interfering with an individual's natural metabolism and causing high blood sugar. Insulin triggers an increase of glucose transport proteins on a cell that facilitates the transfer of glucose out of the bloodstream and into the cell. However, the transport proteins will not work without enough potassium in the blood. Some medications cause a disruption in the healthy potassium levels, resulting in high blood sugar levels because the glucose cannot transfer out of the bloodstream into the cells. 

Medications that reduce potassium in the blood include numerous antimicrobials, beta2-receptor agonists, various diuretics, some laxatives, mineralocorticoids, glucocorticoids, and xanthines. Beta blockers are a type of medication commonly prescribed to treat hypertension, angina, and heart disease. Beta blockers work through a mechanism that interferes with the release of insulin from the pancreas even when blood sugar levels are elevated.

High Blood Pressure

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High blood pressure can contribute to the development of insulin resistance in an affected individual. High blood pressure is when the blood is exerting too much pressure on the arterial walls as it is moving through them. This malfunction can be caused by many factors and can result in numerous complications, including widespread vascular damage. Insulin resistance and high blood pressure both have several similar risk factors including inflammation. The inflammation caused by high blood pressure results in an influx of a type of white blood cell called cytokines. 

Cytokines are known to disrupt the process of insulin signals in the cells of the liver, adipose tissue, and skeletal muscles. This mechanism means the signals from insulin cannot transfer from the outside of the cell to the inside of the cell. The insulin is then unable to perform its function in each of the affected cells, keeping excess glucose in the bloodstream and causing the development of insulin resistance.