What is insulin resistance?
For several reasons, your muscle, fat, and liver cells can respond inappropriately to insulin, which means they cannot efficiently take up glucose from your blood or store it. This is insulin resistance:
1.A lot of blood sugar enters your bloodstream.
2.Your pancreas pumps out high levels of insulin to get more blood sugar into your cells.
3.Over time, your cells stop responding well to insulin, which is known as resistance.
4.Your blood sugar remains high, which causes your pancreas to keep releasing more insulin to make your cells respond; this is called hyperinsulinemia.
5.Eventually, your pancreas cannot keep up and your blood sugar keeps increasing.
High blood sugar is damaging to the body, so your body keeps trying to remove excess blood sugars; it stores extra sugar in your liver and muscles. When they are full, the liver sends the remaining sugar to be stored as body fat, causing weight gain.
In addition to Type 2 diabetes, insulin resistance is associated with several other conditions, including: obesity, cardiovascular disease, nonalcoholic fatty liver disease, metabolic syndrome, and polycystic ovary syndrome (PCOS). Hyperinsulinemia is also associated with higher triglyceride levels, hardening of the arteries (atherosclerosis), and high blood pressure (hypertension).
How common is insulin resistance?
Since there are not any common tests to check for insulin resistance and there are not any symptoms until it turns into prediabetes or Type 2 diabetes, the best way to measure the prevalence of insulin resistance is the number of prediabetes cases.
If you have insulin resistance, but your pancreas can increase insulin production to keep your blood sugar levels in range, you will not have any symptoms. However, over time, the cells in your pancreas that make insulin can wear out. Eventually, your pancreas is no longer able to produce enough insulin to overcome the resistance, leading to elevated blood sugar (hyperglycemia), which causes symptoms.
Certain genetic and lifestyle risk factors make it more likely that you will develop insulin resistance or prediabetes; these include:
- Overweight or obesity, especially excess fat around the belly.
- Being 45 years old or older.
- A first-degree relative (parent or sibling) with diabetes.
- Having a sedentary lifestyle.
- Certain health conditions, such as high blood pressure and abnormal cholesterol levels.
- A history of gestational diabetes.
- A history of heart disease or stroke.
- Having a sleeping disorder such as sleep apnea.
- Smoking.
What causes insulin resistance?
So far, scientists have identified several genes that make a person more or less likely to develop insulin resistance; older people are more prone to insulin resistance. Acquired causes of insulin resistance include:
- Excess body fat: Scientists believe obesity, especially excess fat in the belly and around the organs (visceral fat), is a primary cause of insulin resistance. Studies have shown that belly fat makes hormones and other substances that can contribute to long-term inflammation, which may play a role in insulin resistance.
- Physical inactivity: Physical activity makes your body more sensitive to insulin and builds muscle that can absorb blood glucose. A lack of physical activity can have opposite effects and cause insulin resistance. A sedentary lifestyle is also associated with weight gain, which also contributes to insulin resistance.
- Diet: A diet of highly processed, high-carbohydrate foods and saturated fats has been linked to insulin resistance. The body digests highly processed, high-carbohydrate foods very quickly, which causes blood sugar to spike, putting extra stress on the pancreas to produce a lot of insulin, which can lead to insulin resistance.
- Certain medications can cause insulin resistance, including steroids, some blood pressure medications, and some psychiatric medications.
Hormonal disorders that can cause insulin resistance include:
- Cushing’s syndrome: This happens when there is extra cortisol, the “stress hormone”, in the body. Cortisol is vital to regulating blood sugar levels (by increasing them) and turning food into energy; excess cortisol can counteract the effects of insulin, causing insulin resistance.
- Acromegaly: This is a rare but serious condition that happens when you have high levels of growth hormone (GH). High levels of GH can cause increased production of glucose, which can lead to insulin resistance.
- Hypothyroidism: This happens when the thyroid is underactive and does not produce enough thyroid hormone. The thyroid plays a large role in regulating metabolism; when it makes too little thyroid hormone, it slows down metabolism, including glucose metabolism, which can lead to insulin resistance.
Some inherited conditions that cause insulin resistance include:
- Myotonic dystrophy: This is a form of muscular dystrophy that affects the muscles, eyes, and endocrine system organs, which includes the pancreas. Muscle insulin sensitivity is decreased by about 70% in people with myotonic dystrophy, which leads to insulin resistance.
- Alström syndrome: This is a rare inherited condition that is characterized by a progressive loss of vision and hearing, dilated cardiomyopathy, obesity, Type 2 diabetes, and short stature.
- Werner syndrome: This is a rare progressive disorder that is characterized by the appearance of unusually accelerated aging (progeria). It affects many aspects of the body, including abnormal production of insulin and resistance to its effects.
- Inherited lipodystrophy: This is a condition in which the body does not use and store fat properly. The main cause of insulin resistance in lipodystrophy is that excess glucose cannot be stored in fat tissue.
How is insulin resistance diagnosed?
As there is no single test that can directly diagnose insulin resistance, healthcare providers consider several factors, including medical history, family history, physical exam, signs and symptoms. They may order the following blood tests to diagnose insulin resistance, prediabetes, and/or diabetes:
- Glucose: A fasting plasma glucose (FPG) or a glucose tolerance test (GTT) may be used to screen for, diagnose and/or monitor prediabetes, type 2 diabetes or gestational diabetes.
- Glycated hemoglobin A1c (A1c): This test reveals your average blood glucose levels over the past three months.
- Lipid panel: This is a group of tests that measure specific lipids in your blood, such as total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides.
How to reverse insulin resistance?
Since not all factors that contribute to insulin resistance can be treated, such as genetic factors and age, lifestyle modifications are the primary treatment for insulin resistance:
- Losing excess weight: One study revealed that losing 7% of your excess weight can reduce the onset of Type 2 diabetes by 58%.
- Physical activity: Getting regular amounts of moderate-intensity physical activity helps increase glucose energy usage and improve muscle insulin sensitivity. A single session of moderate-intensity exercise can increase glucose uptake by at least 40%.
- Eating a healthy diet: In general, eating foods that have a low to medium glycemic index and limiting foods that have a high glycemic index can help reverse and/or manage insulin resistance. Eating foods with fiber also helps regulate blood sugar levels because it takes the body longer to digest fiber, meaning blood sugar levels do not spike as much.
The glycemic index (GI) is a measurement that ranks foods containing carbohydrates according to how much they affect blood sugar levels. The Glycemic Index Foundation (GIF) classifies the GI of foods as either low, medium, or high, with pure glucose generally as a reference at 100:
- Low GI: 55 or less.
- Medium GI: 56–69.
- High GI: 70 or greater
High-GI foods generally have a lot of carbohydrates and/or sugar and low to no fiber content; examples include: white bread, potatoes, breakfast cereals, cakes and cookies, fruits such as watermelon and dates.
Low-GI foods generally have low amounts of carbohydrates and higher amounts of fiber; examples include: beans and legumes, fruits such as apples and berries, non-starchy vegetables—such as asparagus, cauliflower, and leafy greens—nuts, dairy, fish, and meat.
Over time, these lifestyle modifications can increase insulin sensitivity (reduce insulin resistance), lower your blood glucose levels, decrease blood pressure, triglyceride, and LDL “bad” cholesterol levels, and raise HDL “good” cholesterol levels.
Sources & References
www.uclahealth.org
www.theguardian.com
www.who.int
www.nhs.uk
www.cdc.gov
https://my.clevelandclinic.org/health/body/22601-insulin
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