With the introduction of Continuous Glucose Monitors (CGMs), insulin resistance has become a more common topic amongst health and wellness communities. What exactly is it, though? Insulin resistance is a condition in which the body's cells become less responsive to the hormone insulin. Produced by the pancreas, insulin plays a critical role in regulating glucose (sugar) levels in our blood. Insulin enables cells to take in glucose to either be used as energy or stored for later use.
When insulin resistance occurs, the normal response to a given amount of insulin is reduced. As a result, the pancreas compensates by producing more insulin. Over time, this leads to higher levels of insulin circulating in the blood, a condition known as hyperinsulinemia. The problem is, despite the high insulin levels, the body's cells can't absorb glucose effectively, causing elevated levels of glucose in the blood. And over time, this can lead to prediabetes, when blood glucose levels are higher than normal but not high enough for a diagnosis of diabetes. If left unchecked and untreated, prediabetes can progress to type 2 diabetes, a chronic condition that affects the way the body processes blood sugar.
That’s not all, though. Insulin resistance is often associated with other serious health conditions, including obesity, high blood pressure, high cholesterol, heart disease, and polycystic ovary syndrome (PCOS). It is a key component of metabolic syndrome, a cluster of conditions that increase the risk of heart disease, stroke, and type 2 diabetes.
How to Detect & Measure Insulin Resistance
The exact cause of insulin resistance is not completely understood, but it is associated with a combination of genetic and lifestyle factors, including lack of physical activity, poor diet, and excess weight, particularly around the waist. In some cases, certain medical conditions and medications can also contribute to insulin resistance.
Regarding genetic variants (SNPs) related to insulin resistance, it's important to remember that while certain SNPs are associated with an increased risk, they do not guarantee the development of insulin resistance, they only signal a potential predisposition. Some well-studied SNPs associated with insulin resistance or related conditions include:
- TCF7L2 (rs7903146): The TCF7L2 gene plays a significant role in blood sugar regulation by affecting insulin production in the pancreas. The variant rs7903146 in this gene is one of the strongest genetic risk factors for type 2 diabetes. People carrying the risk allele (T) may have an increased risk of developing type 2 diabetes.
- PPARG (rs1801282): The PPARG gene produces a protein that plays a role in how the body stores and uses fat. The variant rs1801282, also known as Pro12Ala, is unusual in that the variant allele (G, coding for Ala) is associated with a lower risk of type 2 diabetes, particularly in people who are physically active.
- FTO (rs9939609): The FTO gene cluster is associated with body mass index (BMI) and obesity, which are major risk factors for insulin resistance. The risk allele (A) for the SNP rs9939609 is associated with an increased risk of obesity and, consequently, an increased risk of insulin resistance and type 2 diabetes.
- ABCC8 (rs757110): This gene plays a role in insulin regulation by controlling the release of insulin in response to blood glucose levels. The variant rs757110 in this gene has been associated with an increased risk of type 2 diabetes.
- SLC30A8 (rs13266634): This gene produces a protein involved in the release of insulin. The risk allele (T) for SNP rs13266634 has been linked to an increased risk of type 2 diabetes.
- KCNJ11 (rs5219): The KCNJ11 gene produces a protein that is part of a potassium channel in the pancreas, which plays a key role in the release of insulin. The risk allele (T) for the variant rs5219 has been associated with an increased risk of type 2 diabetes.
In addition to these, numerous other genetic variants have been linked to insulin resistance, type 2 diabetes, and related traits. And, of course, lifestyle factors like diet, exercise, and sleep have a significant influence on these conditions, as well.
Now, if you do have insulin resistance… which biomarkers should we be looking at to measure it:
- Fasting Insulin: This measures your insulin levels after fasting for 8 to 12 hours. High fasting insulin can indicate insulin resistance.
- Fasting Blood Glucose: This test measures your blood glucose levels after fasting for 8 to 12 hours. Elevated fasting glucose can indicate insulin resistance or diabetes.
- HbA1c (Glycated Hemoglobin): This measures your average blood glucose levels over the past 2 to 3 months. A high HbA1c level can indicate poor blood sugar control, suggesting insulin resistance or diabetes.
- Homeostatic Model Assessment of Insulin Resistance (HOMA-IR): This combines your fasting glucose and fasting insulin levels in a formula to calculate insulin resistance.
- Oral Glucose Tolerance Test (OGTT): This test measures your body's response to glucose. It involves fasting overnight and then drinking a solution containing a specific amount of glucose. Blood glucose levels are measured at intervals for 2 to 3 hours.
- Lipid Profile: High levels of triglycerides and low levels of high-density lipoprotein (HDL) cholesterol have been associated with insulin resistance.
The good news is that insulin resistance can often be managed and even reversed through lifestyle modifications. If necessary, certain medications may be used to improve insulin sensitivity. But, with a clear lifestyle regimen and regular monitoring, blood glucose levels can be managed effectively. Let’s discuss how.
How to Monitor Glucose Levels with a CGM
Monitoring glucose levels is a keystone in managing and understanding various health aspects, including insulin resistance and diabetes. The reasons are multifold – with early detection at the top of the list, given insulin resistance is often a silent precursor to type 2 diabetes.
As mentioned, beyond a blood test or oral glucose tolerance test (OGTT), CGMs have become all the rage not only amongst those that are insulin resistant, but biohackers trying to better understand which diet and lifestyle habits allow them to function better.
CGMs are wearable devices that measure glucose levels in real-time by reading the interstitial fluid beneath your skin. They can be an invaluable tool for people with diabetes or those looking to gain a more detailed understanding of how various foods, activities, and stressors affect their blood sugar levels throughout the day. Medical providers can prescribe CGMs, but there are a host of new brands – like Levels, Veri, Supersapians, and January – that sell direct-to-consumer, with sophisticated apps for tracking and monitoring. For more on using a CGM for glucose monitoring, check out this recent episode of the Wild Health Podcast.
Nutritional Optimization for Insulin Resistance
Whether you’re predisposed, working to reverse, or not even worried about insulin resistance, adopting a nutrient-dense, whole foods diet is immensely beneficial. Particularly for insulin resistance, a low-glycemic diet, or one that focuses on foods that minimally impact blood sugar levels, is an important added layer.
The Glycemic Index (GI) is a rating system that assigns a numerical value to foods based on how they affect blood glucose levels. Foods with a high GI value cause a rapid increase in blood sugar levels, whereas those with a low GI value result in a slower, more gradual rise. Consuming low glycemic foods and employing smart food combining strategies can be instrumental in avoiding glucose spikes and managing or preventing insulin resistance.
Glycemic Load (GL), on the other hand, combines both the quality and quantity of carbohydrate in a single number. It's calculated by multiplying the amount of carbohydrate in a food (in grams) by the food's GI and then dividing by 100. Therefore, a low GL food is one that has a low GI and is also low in carbohydrates.
Here are some examples of foods that are low in both GI and GL:
1. Non-Starchy Vegetables: broccoli, spinach, bell peppers, zucchini, tomatoes, cucumbers
2. Whole Grains: barley, bulgur, quinoa, brown rice
3. Legumes: lentils, chickpeas, black beans, kidney beans
4. Fruits: apples, oranges, peaches, pears, berries
5. Nuts & Seeds: almonds, walnuts, sunflower seeds, flax seeds
6. Dairy (for those that can tolerate): milk, Greek yogurt, hard cheeses
In general, foods that are high in fiber or protein tend to have a lower GI and GL because these nutrients slow down the digestion and absorption of carbohydrates, leading to a more gradual rise in blood sugar. So, pairing carbohydrates with a quality protein or fat source will slow down the digestion of the carb and thus the release of sugar into the bloodstream. Another ‘hack’ gaining popularity is adding vinegar or lemon juice to foods and/or taking a diluted shot of ACV before a meal – or even just once a day – to aid in digestion and blood glucose regulation.
However, while GI and GL can be useful tools in planning meals, they should not be the sole focus of your diet. It's also important to consider the nutritional value of foods, and aim for a varied, balanced diet that includes plenty of fruits, vegetables, lean proteins, and healthy fats. It's also important to note that the GI and GL of a food can vary depending on how it's cooked, what it's eaten with, and even from person to person. That’s why personalization and monitoring your own blood sugar response is so important.
Optimal nutrition alongside regular physical activity, stress management, adequate sleep, and personalized supplementation can allow for highly effective management of blood glucose levels and a reduced risk of insulin resistance and its associated complications.
More Resources on Insulin Resistance from the Wild Health Podcast: