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Insulin resistance and its role in type 2 diabetes

When the body is insulin resistant it is less able to convert blood sugar into energy, which can cause negative health effects. However, healthy routines can help reduce insulin resistance in people with type 2 diabetes.
Joanna York
9/13/2022
9
min read
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Quick summary

  • Insulin is a hormone that helps turn food into energy by carrying sugars from the blood into the body’s cells. 
  • Insulin resistance means cells do not absorb sugar from the blood correctly. When this happens blood sugar stays high so the body produces more insulin to try and fix the problem, causing an imbalance.
  • There is no single cause that leads people to develop insulin resistance but the issue is common among people with type 2 diabetes.
  • High blood sugar and insulin levels can cause a range of health problems. For example, people who are insulin resistant could be prone to gaining weight.
  • It is possible to reverse insulin resistance and improve insulin sensitivity through healthy routines including diet and exercise.

Insulin resistance means that the body is struggling to convert food into energy and is a common issue among people with type 2 diabetes. It can impact blood sugar levels, the amount of energy you have, and how well the body is able to regulate weight. 

As such, insulin resistance can lead to other serious health problems, such as heart disease and high blood pressure.

There are some factors that can make people more likely to develop insulin resistance, but there is no single cause for the condition. It is common among people with prediabetes and type 2 diabetes, and the more insulin resistant the body becomes, the more difficult it can be to manage these conditions. 

When insulin can’t do its job properly, sugar levels in the blood stay too high, indicating prediabetes or type 2 diabetes

However, it is possible to reverse insulin resistance and increase insulin sensitivity through healthy habits. Eating a balanced diet and exercising regularly, for example, can help the body respond better to insulin over time.

Understanding how insulin resistance works can also help you better understand what is happening in your body and how to manage it.

What is insulin?

Insulin is a hormone that helps the body turn food into energy. As we digest food, most of it is broken down in the digestive tract into sugar (also called glucose). This sugar is then released into the bloodstream. [1]

As our blood sugar increases, the pancreas (a gland behind the stomach) starts releasing insulin. Insulin helps move the sugar into cells in the muscles and liver where it can be converted into useful energy that helps power the body through the day. 

How does insulin help regulate blood sugar?

When insulin is doing its job correctly, it moves sugar from the blood into cells in the muscles where it can be used as energy. As this happens, the body’s blood sugar levels go down. This sends a signal to the pancreas to stop releasing insulin, and the body’s insulin levels start to go down too. 

When the muscles have enough sugar, insulin helps move any remaining blood sugars to the liver, so that overall blood sugar levels return to a healthy level. This sugar is stored in the liver and released when the body needs more energy, for example, a few hours after eating.

When insulin can’t do its job properly, sugar levels in the blood stay too high. This can indicate prediabetes or type 2 diabetes. 

How does insulin resistance develop?

Insulin resistance (also called impaired insulin sensitivity) is when cells in the body don’t respond to insulin properly. This means that sugar stays in the blood rather than moving to the cells in the muscles or liver. When this happens, blood sugar levels remain high but the body lacks energy. 

Insulin levels in the body can also rise higher than normal, as the pancreas releases more of the hormone to try and fix the problem. Over time the cells respond to all that insulin less well and become insulin resistant.[1]

Scientists have not discovered one exact cause for insulin resistance, but there are factors that make people more vulnerable to the condition. These include a family history of type 2 diabetes, being overweight around the waist, being inactive, chronic stress, and polycystic ovary syndrome, among others. Older people are also more prone to develop insulin resistance.[2]

However, these are just possible indicators that someone may be more likely to develop insulin resistance. It is possible to develop insulin resistance without any of these factors.

Initially, insulin resistance symptoms are not noticeable so you may not know you have it until you get a test. If insulin resistance starts to cause high blood sugar outside of a healthy range, symptoms can include tiredness, hunger, and weight gain.[2]

Tests to find out whether someone is insulin resistant typically measure blood sugar levels. For example, the HbA1c test measures average blood sugar levels over three months [3]. This test is also used to help diagnose prediabetes and type 2 diabetes.

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What are the possible results of insulin resistance?

If insulin resistance is not managed it can cause a range of negative health effects.

One of the most directly linked is weight gain. When cells are insulin resistant, insulin cannot properly transfer blood sugar to the muscles or liver, so it instructs the body to store the sugar for future use in the form of body fat.

Other risks are similar to those posed by type 2 diabetes in general and include heart disease and high blood pressure.

How can I reduce insulin resistance?

Exercise and weight loss

Physical activity can help your body become more sensitive to insulin. Studies have found that exercising for about 25 minutes a day 5 days a week can help reduce insulin resistance, even if the exercise is a low-intensity activity like walking.[4]

This is largely because exercise leads to weight loss which can improve insulin sensitivity,[5] but also because it transforms the metabolism of the body, building strength in the muscles. Weight loss through changes in diet alone does not do this.[6]

Diet

A healthy diet can also help reduce insulin resistance. Studies have found that—as long as they are done in a safe way—fasting or reducing food intake can reduce insulin sensitivity as it can improve how good the pancreas is at producing insulin.[7] 

Eating a diet based on non-processed foods such as vegetables, grains, fruit, meat, fish, and legumes is also a good idea. Studies have also found that low-carb diets can be helpful.[8]

Reduce stress and increase sleep

When under stress the body produces a hormone called cortisol, which can make cells in muscles resistant to insulin.[9] Reducing stress when possible, and making sure that you are getting a good amount of sleep each night will help your body better regulate its blood sugar levels.

Quit smoking

Research shows that there could be a link between nicotine and insulin resistance. As such, stopping or reducing smoking could improve insulin resistance. [10]

Improving insulin sensitivity

When insulin does its job in the body, our energy levels go up and we feel less tired. Improving insulin sensitivity for people with type 2 diabetes can also help lower blood sugar levels and reverse overall diabetes symptoms.  

As we can’t see whether the insulin in our body is working properly or not, reversing insulin resistance can seem like a difficult task. However, following steps that lead to an overall healthy lifestyle—such as exercising, eating a balanced diet and getting enough sleep—are effective ways to help our bodies use insulin properly. 

References

[1] Insulin Resistance and Diabetes. Centers for Disease Control and Prevention. Retrieved 27 March 2022. Accessible here.

[2] Insulin Resistance. Diabetes.co.uk. Retrieved 27 March 2022. Accessible here.

[3] All about your A1C. Centers for Disease Control and Prevention. Retrieved 27 March 2022. Accessible here.

[4] Insulin Resistance. Diabetes Prevention Support Center, University of Pittsburgh. Retrieved 27 March 2022. Accessible here.

[5] Taylor, R., Al-Mrabeh, A., Sattar, N. (2019). Understanding the mechanisms of reversal of type 2 diabetes. Lancet Diabetes Endocrinol 7(9): P726-736. Accessible here.

[6] Keshel, T., Coker, R. (2015). Exercise training and insulin resistance: A current Review. J Obes Weight Loss Ther 5 (05): PS5-003. Accessible here.

[7] Lim, E., Hollingsworth, K., Aribisala, B., et al. (2011). Reversal of type 2 diabetes: normalisation of beta cell function in association with decreased pancreas and liver triacylglycerol. Diabetologia 54(10; P2506-24. Accessible here.

[8] Lin, P., Borer, K. (2016). Third exposure to a reduced carbohydrate meal lowers evening postprandial insulin and GIP responses and HOMAIR estimate of insulin resistance. Plos One 11(10): e0165378. Accessible here.

[9] Blood Sugar and Stress. Diabetes Education Online. Retrieved 27 March 2022. Accessible here.

[10] Li, Z., Xu, W., Su, Y., et al. (2019) Nicotine indices insulin resistance via downregulation of Nrf2 in cardiomyocyte. Mol Cell Endocrinol Epub. Accessible here.

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