HEALTHPLAN MAGAZINE

Insulin resistance is a critical health concern in our modern society, given its association with the escalating rates of type 2 diabetes and metabolic disorders. This article aims to provide a concise and informative overview of insulin resistance, delving into its underlying mechanisms, its implications for blood sugar control and chronic disease development, and practical strategies for its management and potential reversal.

What is Insulin resistance?

Insulin resistance, also referred to as impaired insulin sensitivity, occurs when the cells in your muscles, fat tissue, and liver do not respond appropriately to insulin, a hormone produced by the pancreas that plays a vital role in regulating blood glucose (sugar) levels, essential for sustaining life. Insulin resistance can manifest as either a temporary or chronic condition and is amenable to treatment in some cases.

In normal physiological circumstances, insulin functions through the following steps:

• Your body breaks down the food you consume into glucose (sugar), which serves as the primary energy source for your body.
• Glucose enters your bloodstream, signalling your pancreas to release insulin.
• Insulin facilitates the entry of glucose from your bloodstream into muscle, fat, and liver cells, where it can be utilised for energy or stored for future use.
• As glucose enters your cells and blood glucose levels decrease, your pancreas ceases insulin production.

However, for various reasons, your muscle, fat, and liver cells can respond inadequately to insulin, making it challenging for them to efficiently take up glucose from your bloodstream or store it. This condition is known as insulin resistance. Consequently, your pancreas increases insulin production in an attempt to counteract rising blood glucose levels, a state referred to as hyperinsulinemia.

As long as your pancreas can produce enough insulin to overcome your cells' diminished response to it, your blood sugar levels will remain within a healthy range. However, if your cells become excessively resistant to insulin, it results in elevated blood glucose levels (hyperglycemia), eventually leading to prediabetes and Type 2 diabetes over time.

In addition to Type 2 diabetes, insulin resistance is associated with several other medical conditions, including:

• Obesity.
• Cardiovascular disease.
• Nonalcoholic fatty liver disease.
• Metabolic syndrome.
• Polycystic ovary syndrome (PCOS).

Who Is Affected by Insulin Resistance?

Insulin resistance can affect anyone, regardless of whether they have diabetes. It may be a temporary condition, such as when caused by short-term use of steroid medications, or a chronic condition. Two primary factors associated with insulin resistance are excess body fat, particularly around the abdominal area, and a lack of physical activity.

People with prediabetes and Type 2 diabetes typically exhibit varying degrees of insulin resistance. Even individuals with Type 1 diabetes may experience episodes of insulin resistance.

How Common Is Insulin Resistance?

Since there are no standard tests for directly measuring insulin resistance, and symptoms do not manifest until it progresses to prediabetes or Type 2 diabetes, the prevalence of insulin resistance is best assessed by examining the number of prediabetes cases. In the United States, more than 84 million adults have been diagnosed with prediabetes, representing approximately one-third of all adults.

Impact of Insulin Resistance on the Body

Insulin resistance typically prompts increased insulin production (hyperinsulinemia) to maintain healthy blood sugar levels. Elevated insulin levels can contribute to weight gain, exacerbating insulin resistance.

Hyperinsulinemia is associated with several conditions, including:

• Elevated triglyceride levels.
• Atherosclerosis (hardening of the arteries).
• High blood pressure (hypertension).

Insulin resistance is also a central feature of metabolic syndrome, a cluster of factors that connect excess abdominal fat and insulin resistance to an increased risk of cardiovascular disease, stroke, and Type 2 diabetes. Characteristics of metabolic syndrome include elevated blood glucose levels, high triglycerides, low high-density lipoprotein (HDL) cholesterol, and high blood pressure. Not all four features need to be present for a diagnosis of metabolic syndrome.

What are the Symptoms and Causes of Insulin Resistance?

Symptoms of insulin resistance are often absent if the pancreas can compensate by increasing insulin production to maintain blood sugar levels within the normal range. However, as insulin resistance worsens and the pancreas struggles to produce sufficient insulin, symptoms may become apparent. High blood sugar (hyperglycemia) can lead to symptoms such as increased thirst, frequent urination, increased hunger, blurred vision, headaches, and susceptibility to infections.

Prediabetes is frequently asymptomatic, with symptoms only emerging as it progresses to Type 2 diabetes. Some individuals with prediabetes may experience signs such as darkened skin in the armpits and neck (acanthosis nigricans), skin tags, and eye changes related to diabetes-related retinopathy.

Insulin resistance can have various causes and contributing factors, with ongoing research seeking to elucidate its development further. Genetic predisposition and advancing age are among the identified factors.

What conditions can contribute to varying degrees of insulin resistance?

• Excess body fat: Obesity, particularly visceral fat (fat stored around organs), is believed to be a primary contributor to insulin resistance. Abdominal obesity, defined by a waist measurement of 40 inches or more for men and assigned males at birth, and 35 inches or more for women and assigned females at birth, is linked to insulin resistance. Belly fat produces hormones and substances that promote chronic inflammation, potentially exacerbating insulin resistance.
• Physical inactivity: Regular physical activity enhances insulin sensitivity and promotes muscle glucose uptake. A sedentary lifestyle, on the other hand, can worsen insulin resistance and lead to weight gain.
• Diet: Consuming a diet rich in highly processed, high-carbohydrate foods and saturated fats has been associated with insulin resistance. Such foods cause rapid spikes in blood sugar, necessitating increased insulin production over time, potentially leading to insulin resistance.
• Certain medications: Some medications, including steroids, certain blood pressure drugs, specific HIV treatments, and some psychiatric medications, can induce insulin resistance.

Insulin resistance can also result from hormonal disorders, affecting the body's insulin utilisation.

These disorders include:

• Cushing's syndrome: Excess cortisol in the body can counteract insulin's effects, leading to insulin resistance.
• Acromegaly: Elevated growth hormone (GH) levels can stimulate excessive glucose production, contributing to insulin resistance.
• Hypothyroidism: An underactive thyroid leads to reduced metabolism, affecting glucose metabolism and potentially causing insulin resistance.

Inherited genetic conditions can also cause insulin resistance. Notable conditions within this category include:

• Type A insulin resistance syndrome: This condition can lead to insulin resistance and diabetes, typically becoming evident after puberty.
• Rabson-Mendenhall syndrome: Characterised by stunted growth and diabetes-related complications, this syndrome often appears early in life and may lead to complications.
• Donohue syndrome: This syndrome, presenting with growth difficulties and other symptoms, typically manifests early in life and is associated with high mortality rates.
• Myotonic dystrophy: This muscular dystrophy variant affects muscles, eyes, and the pancreas, contributing to insulin resistance.
• Alström syndrome: A rare condition involving vision and hearing loss, cardiomyopathy, obesity, and Type 2 diabetes.
• Werner syndrome: This progressive disorder accelerates ageing and affects insulin production and sensitivity.
• Inherited lipodystrophy: This condition disrupts fat storage and utilisation, leading to insulin resistance.

Diagnosis and Tests for Insulin Resistance

Insulin resistance is challenging to diagnose directly because there are no standardised tests for it. It often remains asymptomatic until it progresses to prediabetes or Type 2 diabetes. Healthcare providers assess insulin resistance based on factors such as medical history, family history, physical examination, symptoms, and test results.

To evaluate insulin resistance and related conditions, healthcare providers may order the following blood tests:

• Glucose tests: These include fasting plasma glucose (FPG) and glucose tolerance tests (GTT) to screen for, diagnose, or monitor prediabetes, Type 2 diabetes, or gestational diabetes.
• Glycated haemoglobin A1c (A1c): This test provides an average of blood glucose levels over the past three months.
• Lipid panel: This group of tests measures various lipids in the blood, including total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides.

Providers may also order tests to diagnose associated conditions such as metabolic syndrome, cardiovascular disease, and polycystic ovary syndrome (PCOS).

How can you manage and treat Insulin Resistance?

The primary approach to managing insulin resistance involves lifestyle modifications, as not all contributing factors can be treated, particularly genetic and age-related factors. Lifestyle changes include:

• Healthy diet: Reducing excessive carbohydrate consumption, particularly processed and high-carbohydrate foods, along with limiting unhealthy fats, sugars, red meats, and processed starches. A focus on whole foods, including vegetables, fruits, whole grains, fish, and lean poultry, is often recommended.
• Physical activity: Regular moderate-intensity exercise can improve glucose utilisation and enhance muscle insulin sensitivity. A single session of moderate-intensity exercise can significantly increase glucose uptake.
• Weight loss: Losing excess weight, as little as 7% of excess body weight, can significantly reduce the risk of Type 2 diabetes.

Over time, these lifestyle changes can:

• Enhance insulin sensitivity (reduce insulin resistance).
• Lower blood glucose levels.
• Reduce blood pressure.
• Lower triglycerides and LDL ("bad") cholesterol levels.
• Increase HDL ("good") cholesterol levels.

While no medications directly treat insulin resistance, healthcare providers may prescribe medications to manage concurrent conditions. These medications could include blood pressure medications, metformin for diabetes, or statins to lower LDL cholesterol levels.

Reversing insulin resistance may be possible through lifestyle changes, but not all causes are reversible. Consulting with a healthcare provider is essential to determine the best approach for managing insulin resistance.

Impact of Diet on Insulin Resistance: Diet significantly influences blood sugar and insulin levels. Highly processed, high-carbohydrate, and high-fat foods often require more insulin for processing.

In general, consuming foods with a low to medium glycemic index (GI) and limiting high-GI foods can help manage and potentially reverse insulin resistance. Foods high in fibre also help regulate blood sugar levels by slowing down digestion, reducing blood sugar spikes.
The glycemic index (GI) categorises carbohydrate-containing foods based on their impact on blood sugar levels. It classifies foods as low, medium, or high GI, using pure glucose as a reference with a score of 100:

• Low GI: 55 or lower.
• Medium GI: 56–69.
• High GI: 70 or higher.

High-GI foods typically have a higher carbohydrate or sugar content and lower fibre content. In contrast, low-GI foods generally contain fewer carbohydrates and more fibre. Examples of high-GI foods include white bread, potatoes, breakfast cereals, cakes, cookies, and certain fruits like watermelon and dates. Low-GI foods include beans, legumes, fruits like apples and berries, non-starchy vegetables (e.g., asparagus, cauliflower, leafy greens), nuts, and lean proteins (e.g., dairy, fish, meat).

Before making significant dietary changes, it is advisable to consult with a healthcare provider.

How can you prevent Insulin resistance?

Several genetic and lifestyle factors can increase the risk of developing insulin resistance or prediabetes. Risk factors include:

• Overweight or obesity, particularly abdominal obesity.
• Age 45 or older.
• A family history of diabetes.
• Sedentary lifestyle.
• Certain health conditions, such as high blood pressure and abnormal cholesterol levels.
• History of gestational diabetes.
• History of heart disease or stroke.
• Sleep disorders, including sleep apnea.
• Smoking.

Certain racial and ethnic backgrounds also carry a higher risk of insulin resistance and prediabetes, including Asian Americans, Black individuals, Hispanic/Latino populations, Indigenous people from Alaska, Indigenous people from the continental United States, and Indigenous people from the Pacific Islands.

While some risk factors, such as age and family history, cannot be modified, lifestyle changes can help reduce the risk of developing insulin resistance. Maintaining a healthy weight, adopting a balanced diet, and engaging in regular exercise are essential strategies for prevention.

Outlook and Prognosis for Insulin Resistance

The outlook (prognosis) for individuals with insulin resistance varies depending on several factors:

• The underlying cause of insulin resistance.
• The severity of insulin resistance.
• The functionality of insulin-producing cells.
• Susceptibility to complications.
• Adherence to treatment and the individual's response to treatment.

Some individuals may have mild insulin resistance that does not progress to prediabetes or Type 2 diabetes. For others, insulin resistance may be reversible or manageable with lifestyle changes. However, individuals with severe inherited conditions causing insulin resistance may face life-threatening consequences or complications.

Regular medical follow-ups and adherence to treatment plans are crucial for managing insulin resistance and preventing potential complications.

Complications of Insulin Resistance

Complications associated with insulin resistance often stem from elevated blood sugar (hyperglycemia) and increased insulin levels (hyperinsulinemia). Not everyone with insulin resistance will experience complications, but those diagnosed with insulin resistance, Type 2 diabetes, or metabolic syndrome should receive regular medical care to reduce the risk of complications.

Living with Insulin Resistance

Individuals diagnosed with insulin resistance or related conditions should maintain regular follow-ups with their healthcare providers to ensure that blood sugar levels remain within a healthy range and that treatment plans are effective.

If experiencing symptoms of high blood sugar or prediabetes, individuals should promptly contact their healthcare providers for assessment and appropriate testing.

For those with a family history of diabetes or risk factors for insulin resistance, open discussions with healthcare providers can help assess and manage the risk effectively.

Disclaimer

The information provided in this article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. It is important to consult with a qualified healthcare professional for personalised guidance regarding your specific health situation, including any concerns related to insulin resistance or any other medical condition. Never disregard professional medical advice or delay seeking it because of something you have read in this article. If you think you may have a medical emergency, call your doctor or emergency services immediately. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Reliance on the information in this article is solely at your own risk.