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Insulin Resistance

What is the meaning of Insulin Resistance?

Insulin resistance is identified as an impaired biologic response to insulin stimulation of target tissues, primarily the liver, muscle, and adipose tissue. Insulin resistance impairs glucose disposal, resulting in a compensatory increase in beta-cell insulin production and hyperinsulinemia. The metabolic consequences of insulin resistance can result in hyperglycemia, hypertension, dyslipidemia, visceral adiposity, hyperuricemia, elevated inflammatory markers, endothelial dysfunction, and a prothrombic state. Progression of insulin resistance can lead to metabolic syndrome, nonalcoholic fatty liver disease (NAFLD), and type 2 diabetes mellitus.

normal circumstances, insulin functions in the following steps:

1. Your body breaks down the food you eat into glucose (sugar), which is your body’s main source of energy.
2. Glucose enters your bloodstream, which signals your pancreas to release insulin.
3. Insulin helps glucose in your blood enter your muscle, fat and liver cells so they can use it for energy or store it for later use.
4. When glucose enters your cells and the levels in your bloodstream decrease, it signals your pancreas to stop producing insulin.
5. For several reasons, your muscle, fat and liver cells can respond inappropriately to insulin, which means they can’t efficiently take up glucose from your blood or store it. This is insulin resistance. As a result, your pancreas makes more insulin to try to overcome your increasing blood glucose levels. This is called hyperinsulinemia. As long as your pancreas can make enough insulin to overcome your cells’ weak response to insulin, your blood sugar levels will stay in a healthy range. If your cells become too resistant to insulin, it leads to elevated blood glucose levels (hyperglycemia), which, over time, leads to prediabetes and Type 2 diabetes. In addition to Type 2 diabetes, insulin resistance is associated with several other conditions, including:
6. obesity
7. cardiovascular
8. Nonalcoholic fatty liver disease.
9. Metabolic syndrome
10. Polycystic ovary syndrome (pcos) .

Who does insulin resistance affect?

Insulin resistance can affect anyone — you don’t have to have diabetes — and it can be temporary (for example, using steroid medication for a brief period causes insulin resistance) or chronic. The two main factors that seem to contribute to insulin resistance are excess body fat, especially around your belly, and a lack of physical activity.

People who have prediabetes and Type 2 diabetes usually have some level of insulin resistance. People with Type 1 diabetes can also experience insulin resistance.

SYMPTOMS AND CAUSES

What are the symptoms of insulin resistance?

If you have insulin resistance, but your pancreas can increase insulin production to keep your blood sugar levels in range, you won’t have any symptoms.

However, over time, insulin resistance can get worse, and 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 does cause symptoms.

Symptoms of high blood sugar include:

1. Increased thirst.
2. Frequent urinating
3. Increased huunger.
4. Blurred vision.
5. Headache.
6. Vaginal and skin infections.
7. Slow-healing cuts and sores.

Many people have no symptoms of prediabetes, often for years. Prediabetes may be invisible until it develops into Type 2 diabetes. Some people with prediabetes may experience the following symptoms:

1. Darkened skin in your armpit or back and sides of your neck, called acanthosis nigricans.
2. Skin tags (small skin growths).
3. Eye changes that can lead to diabetes related retinopathy

What causes insulin resistance?

Scientists still have a lot to discover about how exactly insulin resistance develops. So far, they’ve identified several genes that make a person more or less likely to develop insulin resistance. In addition, older people are more prone to insulin resistance.

Several factors and conditions can cause varying degrees of insulin resistance. Scientists believe that excess body fat, especially around your belly, and physical inactivity are the two main contributing factors to insulin resistance.

Acquired causes of insulin resistance

Acquired causes, meaning you’re not born with the cause, of insulin resistance include:

1. Excess body fat: Scientists believe obesity, especially excess fat in your belly and around your organs (visceral fat), is a primary cause of insulin resistance. A waist measurement of 40 inches or more for men and people assigned male at birth and 35 inches or more for women and people assigned female at birth is linked to insulin resistance. Studies have shown that belly fat makes hormones and other substances that can contribute to long-term inflammation in your body. This inflammation may play a role in insulin resistance
2. 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. In addition, a lack of physical activity and a sedentary lifestyle are associated with weight gain, which can also contribute to insulin resistance.
3. Diet: A diet of highly processed, high-carbohydrate foods and saturated fats has been linked to insulin resistance. Your body digests highly processed, high-carbohydrate foods very quickly, which causes your blood sugar to spike. This puts extra stress on your pancreas to produce a lot of insulin, which, over time, can lead to insulin resistance.
4. Certain medications: Certain medications can cause insulin resistance, including steroids, some blood pressure medications, certain HIV treatments and some psychiatric medications.

DIAGNOSIS AND TESTS

How is insulin resistance diagnosed?

Insulin resistance is difficult to diagnose because there isn’t routine testing for it, and as long as your pancreas is producing enough insulin to overcome the resistance, you won’t have any symptoms.

As there’s no single test that can directly diagnose insulin resistance, your healthcare provider will consider several factors when assessing insulin resistance, including your:

1. Medical history.
2. Family history.
3. Physical exam.
4. Signs and symptoms.
5. Test results.

MANAGEMENT AND TREATMENT

How is insulin resistance treated?

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. Lifestyle modifications include:

1. Eating a healthy diet: Your healthcare provider or nutritionist may recommend avoiding eating excessive amounts of carbohydrates (which stimulate excess insulin production) and eating less unhealthy fat, sugar, red meats and processed starches. Instead, they’ll likely recommend eating a diet of whole foods that includes more vegetables, fruits, whole grains, fish and lean poultry.
2. 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%.
3. Losing excess weight: Your healthcare provider may recommend trying to lose excess weight to try treating insulin resistance. One study revealed that losing 7% of your excess weight can reduce the onset of Type 2 diabetes by 58%.

Over time, these lifestyle modifications can:

1. Increase insulin sensitivity (reduce insulin resistance).
2. Lower your blood glucose levels.
3. Decrease blood pressure.
4. Decrease triglyceride and LDL (“bad”) cholesterol levels.
5. Raise HDL (“good”) cholesterol levels.

How can diet affect insulin resistance?

Your diet has a big impact on your blood sugar and insulin levels. Highly processed, high-carbohydrate and high-fat foods require more insulin.

In general, eating foods that have a low to medium glycemic index and limiting foods that have a high glycemic index can help you reverse and/or manage insulin resistance. Eating foods with fiber also helps regulate blood sugar levels because it takes your body longer to digest fiber, meaning your blood sugar levels don’t spike as much.

The glycemic index (GI) is a measurement that ranks foods containing carbohydrates according to how much they affect your 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:

1. Low GI: 55 or less.
2. Medium GI: 56–69.
3. High GI: 70 or greater

High-GI foods generally have a lot of carbohydrates and/or sugar and low to no fiber content. Low-GI foods generally have low amounts of carbohydrates and higher amounts of fiber.

Examples of foods with a high GI include:

1. White bread.
2. Potatoes.
3. Breakfast cereals.
4. Cakes and cookies.
5. Fruits such as watermelon and dates.

Examples of foods with a low GI include:

1. Beans and legumes.
2. Fruits such as apples and berries.
3. Non-starchy vegetables, such as asparagus, cauliflower and leafy greens.
4. Nuts.
5. Dairy, fish and meat.

References

1. Seong J, Kang JY, Sun JS, Kim KW. Hypothalamic inflammation and obesity: a mechanistic review. Arch Pharm Res. 2019 May;42(5):383-392. [PubMed]

2. Brown JC, Harhay MO, Harhay MN. The Value of Anthropometric Measures in Nutrition and Metabolism: Comment on Anthropometrically Predicted Visceral Adipose Tissue and Blood-Based Biomarkers: A Cross-Sectional Analysis. Nutr Metab Insights. 2019;12:1178638819831712. [PMC free article] [PubMed]

3. Deacon CF. Physiology and Pharmacology of DPP-4 in Glucose Homeostasis and the Treatment of Type 2 Diabetes. Front Endocrinol (Lausanne). 2019;10:80. [PMC free article] [PubMed]

4.American Diabetes Association. Understanding Insulin Resistance. (https://www.diabetes.org/healthy-living/medication-treatments/insulin-resistance) Accessed 12/16/2021.

5.Centers for Disease Control and Prevention. Insulin Resistance and Diabetes. (https://www.cdc.gov/diabetes/basics/insulin-resistance.html) Accessed 12/16/2021.

6.Freeman AM, Pennings N. Insulin Resistance. (https://www.ncbi.nlm.nih.gov/books/NBK507839/) [Updated July 10, 2021]. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2021. Accessed 12/16/2021.

7.Lab Tests Online. Insulin Resistance. (https://labtestsonline.org/conditions/insulin-resistance) Accessed 12/16/2021.

8. National Institute of Diabetes and Digestive and Kidney Diseases. Insulin Resistance & Prediabetes. (https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance) Accessed 12/16/2021.