Insulin resistance is a major health problem worldwide.
It is referred to as a "global epidemic”. It is certainly one of the most pressing health issues of the 21st century.
Does anyone care?
What you need to know:
What is insulin resistance?
Insulin resistance occurs when the cells in your muscles, fat, and liver don’t respond well to insulin – a fat-storage hormone produced by the pancreas that allows your body to use glucose for energy.
When these cells become resistant, they can't easily take up glucose from your blood. As a result, the pancreas compensates by producing more insulin (to help glucose enter the cells).
This extra work leads to higher blood sugar levels and, eventually, type 2 diabetes, and wears out the pancreas.
This leads to hyperglycaemia (high blood sugar,) and a cascade of health problems – including heart disease, chronic inflammation, oxidative stress, and metabolic syndrome.
IR is seen as a key factor in the development of metabolic disorders.
It is often a precursor to type 2 diabetes, but not everyone with insulin resistance will develop the disease. However, managing insulin resistance is crucial to preventing the progression to type 2 diabetes.
The science behind insulin resistance
A number of studies have shed light on the molecular mechanisms underlying insulin resistance.
A 2023 article written by researchers led Mirvana T. Macvanin and published in the journal Frontiers in Endocrinology cites lab data which shows that Type 2 Diabetes Mellitus (T2DM), which accounts for 90 per cent of all cases of diabetes, is primarily caused by insulin resistance.
It is considered a global health crisis characterised by hyperglycemia, resulting from insulin resistance, inadequate insulin secretion, or excessive glucagon secretion.
DM leads to significant morbidity and mortality worldwide.
A study led by Yehiel Zick, published in the journal Trends in Cell Biology, offers insights into how insulin resistance develops at the cellular level.
The research team found that agents inducing IR exploit the body's phosphorylation-based negative-feedback control mechanisms.
These mechanisms, which are normally used by insulin itself, “uncouple” the insulin receptor from its downstream effectors, which terminates insulin signal transduction.
In short, this means that insulin resistance can disrupt the normal signaling pathways that allow insulin to do its job.
When these pathways are disrupted, the body can't efficiently manage glucose, leading to higher blood sugar levels, increased insulin production.
The net effect: nerve issues, vision problems associated with diabetes. There's also a higher risk of heart attacks.
Insulin resistance vs. Type 1 diabetes
While insulin resistance is often associated with type 2 diabetes, it’s important to distinguish it from type 1 diabetes, which is a different condition altogether.
In contrast, type 1 diabetes is an autoimmune disease where the body attacks the insulin-producing cells in the pancreas. As a result, people with type 1 diabetes produce little to no insulin and must rely on insulin injections to manage their blood sugar levels.
In essence, while both conditions involve problems with insulin, insulin resistance is about the body's inability to use insulin effectively; type 1 diabetes, on the other hand, is about the body's inability to produce enough insulin.
Explaining insulin resistance to kids
When explaining insulin resistance to children, it’s helpful to use simple analogies.
You can think of insulin as a key that unlocks the door to a cell so glucose (sugar) can get inside and be used for energy. In insulin resistance, the lock on the door becomes rusty and hard to turn, so the key (insulin) doesn’t work as well.
This makes it difficult for glucose to get into the cells, and the body has to make more keys (insulin) to try to open the doors.
Expert's take
Dr. Robert Lustig, a prominent endocrinologist and professor of pediatrics at the University of California, San Francisco, is well-known for his work on obesity, metabolic syndrome, and insulin resistance. He has extensively discussed the causes of insulin resistance and strategies to combat it, focusing particularly on the role of diet and lifestyle.
Why insulin resistance called 'a growing epidemic'?
The rise of insulin resistance is closely linked to lifestyle factors, particularly the increase in obesity and physical inactivity.
As more people adopt diets that are high in processed foods and low in physical activity, the prevalence of insulin resistance continues to grow.
Moreover, insulin resistance doesn’t only lead to type 2 diabetes. It is also associated with a range of other health issues, including cardiovascular disease and non-alcoholic fatty liver disease (NAFLD).
These conditions, in turn, contribute to the overall burden of chronic disease in many populations, making insulin resistance a critical public health issue.
Dr. Lustig argues that excessive sugar consumption, particularly fructose, is a major driver of insulin resistance. When the liver is overwhelmed by high sugar intake, it converts excess sugar into fat, leading to non-alcoholic fatty liver disease (NAFLD) and subsequent insulin resistance.
IR and metabolic syndrome:
In “Fructose: metabolic, hedonic, and societal parallels with ethanol” published in the Journal of the American Dietetic Association, Dr. Lustig emphasises that insulin resistance is at the core of “metabolic syndrome”, a cluster of conditions that increase the risk of heart disease, stroke, and type 2 diabetes. This is due to poor diet, particularly one high in processed foods and sugar, in driving insulin resistance and metabolic syndrome.
How to fight IR: Dietary recommendations
To fight insulin resistance, Dr. Lustig and fellow researchers including Laura A Schmidt, Claire D Brindis advocate for a diet low in sugar and processed foods and high in fiber. In “Public health: The toxic truth about sugar,” published in Nature, they stress the importance of whole, unprocessed foods that do not spike blood sugar levels and thus do not overwork the insulin system.
Exercise and insulin sensitivity:
He also highlights the role of regular physical activity in improving insulin sensitivity. In his landmark 2013 book "Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease" (Hudson Street Press), Dr Lustig shows how exercise helps reduce fat accumulation, particularly visceral fat, which is closely linked to insulin resistance.
Moreover, he said, physical activity increases the muscles' ability to take up glucose in response to insulin, thereby lowering insulin resistance.
Sleep and stress management:
He notes that poor sleep and chronic stress contribute to insulin resistance. Both inadequate sleep and high stress levels lead to elevated cortisol levels. This, Dr Lustig explains, can promote insulin resistance and fat storage, especially around the abdomen.
Takeaways
Despite significant advancements in understanding IR, it remains a complex and challenging condition. Understanding the mechanisms behind insulin resistance, and the lifestyle factors contributing to its rise is essential for managing and preventing this condition.
As research continues to uncover the complexities of insulin resistance, it’s crucial to promote healthy lifestyles that can help mitigate its impact on public health.
What's clear is that dealing with insulin resistance is closely linked to long-term wellness.
Note: This information is for general knowledge only. Please consult with your healthcare provider for personalised medical advice.
