Blood Sugar Imbalances, Fluoride, Leptin Resistance

Welcome to Healthy Gut Healthy Thyroid!

This is your weekly roundup of the BEST actionable steps for those people with thyroid and autoimmune thyroid conditions who want to restore their health…by healing their gut. Whether you have hyperthyroidism or Hashimoto’s you will benefit from the content in this newsletter.

In today's issue:

• Announcement: Free 5-Day Accelerated Thyroid Healing Challenge

• Main Topic: How blood sugar imbalances affect the gut and thyroid

• Podcast Review: How big of a concern is fluoride when it comes to thyroid health?

• Understand Your Tests: Understanding blood sugar markers

• Ask Dr. Eric: How can I treat leptin resistance?

How Blood Sugar Imbalances Affect the Gut and Thyroid

Many people with thyroid conditions also experience blood sugar imbalances, and it’s important to understand that you don’t need to be diabetic to face serious consequences. Dysregulated blood sugar can increase the risk of cardiovascular disease, non-alcoholic fatty liver disease, cognitive decline, and even certain types of cancer.

What Is Insulin?

Insulin is a peptide hormone secreted by the beta cells of the pancreas. Its primary function is to help regulate blood glucose levels by facilitating the uptake of glucose into cells. Insulin also influences carbohydrate, fat, and protein metabolism and promotes cell division and tissue growth.¹

With insulin resistance, cells become less responsive to insulin, which forces the pancreas to produce even more of it. Over time, persistently elevated insulin can lead to further metabolic dysfunction and chronic disease.

The Thyroid–Blood Sugar Connection

Thyroid hormones significantly influence glucose metabolism. Research shows that:

In hyperthyroidism, impaired glucose tolerance is primarily linked to hepatic (liver) insulin resistance.²

In hypothyroidism, insulin resistance tends to affect peripheral tissues, such as muscle and fat.²

Thyroid dysfunction not only disrupts blood sugar regulation but can also make it more difficult to manage insulin resistance.

Insulin Resistance and Thyroid Nodules

Numerous studies have explored the link between insulin resistance and thyroid nodule formation:

Elevated insulin levels may stimulate thyroid cell proliferation and increase nodule size and vascularization.³ Some studies found a higher prevalence of benign thyroid nodules in individuals with insulin resistance.⁴

Other studies showed that people with type 2 diabetes have a greater risk of developing thyroid nodules, suggesting a shared metabolic mechanism.⁵

The Impact of the Gut Microbiome on Blood Sugar

An unhealthy gut microbiome can significantly contribute to blood sugar dysregulation. Here’s how:

The gut microbiota regulates nutrient absorption, energy extraction, and short-chain fatty acid (SCFA) production, all of which influence insulin sensitivity.⁶

Dysbiosis, or an imbalance in the gut flora, has been linked to increased systemic inflammation, impaired glucose metabolism, and a higher risk of insulin resistance.^7,8

Certain strains of beneficial bacteria such as Akkermansia muciniphila and Bifidobacterium have been shown to improve glucose tolerance and reduce inflammation.⁹

Increased gut permeability (“leaky gut”) caused by microbial imbalance may lead to immune activation and insulin signaling disruption.

Improving gut health through diet, probiotic foods and supplements, and other treatment options can support better blood sugar regulation and potentially reduce the risk of insulin resistance-related thyroid complications.

How to Balance Blood Sugar Levels

Minimize Refined Foods and Added Sugars. Cutting back on processed carbohydrates and sugary snacks reduces glucose spikes and improves insulin sensitivity. Emphasize whole, fiber-rich foods to promote stable blood sugar levels.

Incorporate Regular Physical Activity. Movement improves insulin sensitivity by helping muscles absorb glucose more efficiently. Even moderate exercise like walking, yoga, or strength training can have a profound impact on metabolic health.

Reduce Inflammation. Chronic inflammation interferes with insulin signaling. Anti-inflammatory foods (like fatty fish, leafy greens, and berries), stress management, and adequate sleep all help reduce inflammation.

Optimize Gut Health. Support your gut microbiome with fermented foods, prebiotics, and high-quality probiotics. Avoid unnecessary antibiotics and address gut infections when present.

Consider Key Supplements. Certain supplements have been shown to support blood sugar balance, including the following:

✅ Chromium: Enhances insulin action

✅ Berberine: Improves glucose and lipid metabolism

✅ Alpha-lipoic acid: Reduces oxidative stress and improves insulin sensitivity

✅ Magnesium: A common deficiency in people with insulin resistance

Conclusion

Blood sugar imbalances are common in people with thyroid conditions and can contribute to or exacerbate thyroid-related complications, including the development of thyroid nodules. Because of the complex relationship between thyroid function, gut health, and insulin signaling, it’s wise to take a holistic approach.

By supporting the gut microbiome, minimizing inflammatory triggers, and focusing on diet and lifestyle modifications, you can take powerful steps toward regulating blood sugar levels and optimizing thyroid function.

Free 5-Day Accelerated Thyroid Healing Challenge

If you have a thyroid or autoimmune thyroid condition and have restored your health through dietary changes alone...then this challenge probably IS NOT for you.

While some people receive excellent results with making changes to their diet, the truth is that eating well alone usually isn't sufficient to restore your thyroid and immune system health.

Don't get me wrong, as eating well is important, and a small percentage of people are able to restore their thyroid and immune system health by eliminating gluten and other common food allergens.

But this isn't the case with most people who have a thyroid or autoimmune thyroid condition, which is why I decided to put together this challenge.

Healthy Immune System = Healthy Thyroid Gland?

Even though the challenge is entitled the "Accelerated Thyroid Healing Challenge", most people with thyroid conditions have Graves' disease or Hashimoto's (and sometimes they have the antibodies to both). While this challenge can also benefit people with non-autoimmune thyroid conditions, for those with thyroid autoimmunity, having a healthy immune system is important to achieve optimal thyroid health.

Click Here to register for the free 5-day challenge

During this 5-day challenge you will…

• Learn how to overcome both common and overlooked "roadblocks" that are preventing your thyroid/immune system from healing

• Discover how to reduce your "toxic thyroid"

• ​Find out why removing the trigger doesn't always break the chronic inflammatory cycle associated with Graves' disease and Hashimoto's, and what you can do to stop this cycle

• ​Discover some of the "hidden" thyroid triggers

• ​Create your thyroid/immune healing action plan

Click Here to register for the free 5-day challenge

Save My Thyroid Podcast Review

I have a podcast called "Save My Thyroid", where I discuss how people with hyperthyroidism and Hashimoto's can save their thyroid and regain their health. And during each edition of this newsletter I'll briefly discuss a recent podcast episode.

In a recent Q & A podcast episode I answered the question “How big of a concern is fluoride when it comes to thyroid health?” In this episode I break down the truth about fluoride, including the synthetic kind added to our water and toothpaste, and how it could be harming your thyroid health. We’ll talk about why this industrial byproduct, which was once used to suppress overactive thyroids, might be disrupting your hormones right now. Plus, I’ll show you how to test your fluoride levels and explain why this is especially important if you have Hashimoto’s or hypothyroidism.

Understand Your Tests

Understanding Blood Sugar Markers

When evaluating blood sugar regulation, most conventional practitioners start by ordering a fasting blood glucose test. While this can be a useful screening tool, it provides only a snapshot of glucose levels at a single point in time and does not offer insight into insulin dynamics or long-term glycemic control.

In functional medicine, a more comprehensive approach is essential for identifying early imbalances and preventing metabolic dysfunction. Below are three common blood sugar markers that can be tested at nearly any standard laboratory:

Fasting Glucose (see Patient Test #1) 

What it measures: The amount of glucose in the blood after at least 8 hours of fasting.

What it means: A fasting glucose level between 70–99 mg/dL is typically considered normal, although an optimal range would be between 70-90 mg/dL. Levels between 100–125 mg/dL suggest impaired fasting glucose (pre-diabetes), while a level ≥126 mg/dL on two separate occasions is diagnostic for diabetes.

Limitations: Fasting glucose does not reflect postprandial (after-meal) glucose spikes or long-term glucose control. It can also be temporarily affected by stress, illness, or medications.

Fasting Insulin (see Patient Test #2)

What it measures: The amount of insulin in the blood after fasting.

What it means: Elevated fasting insulin is often one of the earliest signs of insulin resistance, even when glucose levels remain normal. An optimal fasting insulin range is generally considered to be 2–5 μIU/mL.

Clinical tip: If fasting glucose is normal but insulin is elevated, it usually is an early warning sign of metabolic dysfunction.

Hemoglobin A1C (see Patient Test #3)

What it measures: The percentage of glycated hemoglobin, reflecting average blood glucose levels over the past 2–3 months.

What it means:

Normal: <5.7%

Pre-diabetes: 5.7–6.4%

Diabetes: ≥6.5%

Limitations: Hemoglobin A1C can be influenced by factors such as anemia, iron deficiency, or recent blood loss.

Additional Ways to Evaluate Blood Sugar Imbalances

While the above three markers are useful, there are other tests and tools that can provide deeper insight:

Oral Glucose Tolerance Test. This test involves drinking a glucose solution and measuring blood glucose at intervals (typically 0, 1, and 2 hours). It helps evaluate how effectively the body processes glucose and is especially useful for diagnosing impaired glucose tolerance or gestational diabetes.

C-Peptide. C-peptide is a byproduct of insulin production and reflects endogenous (natural) insulin secretion. Measuring C-peptide can help to distinguish between insulin resistance and reduced insulin production, which can be useful in differentiating type 1 from type 2 diabetes.

Continuous Glucose Monitoring (CGM). CGM devices track blood glucose levels in real-time throughout the day and night. This provides valuable insight into glucose trends, post-meal spikes, overnight lows, and individual responses to specific foods and lifestyle habits.

CGMs are especially useful for those with reactive hypoglycemia, insulin resistance, or type 1 and type 2 diabetes, although these days many people without these conditions are using them.

Ask Dr. Eric

During every issue I'll answer a question or two that I think can benefit most people with a thyroid or autoimmune thyroid condition. If you'd like for me to consider your question for a future edition of this newsletter email your question to [email protected].

QUESTION: HOW CAN I TREAT LEPTIN RESISTANCE?

Dr. Eric, what do you recommend to treat leptin resistance, and will this help me to lose weight?

Thanks for your question! Leptin is a hormone secreted by fat cells that plays a vital role in regulating appetite and energy balance. By signaling the brain to suppress appetite and increase energy expenditure, leptin helps maintain a healthy body weight.

However, when leptin signaling becomes impaired—a condition known as leptin resistance can develop, where the brain no longer responds appropriately to this hormone, often leading to increased hunger, reduced energy expenditure, and weight gain.

What Causes Leptin Resistance?

Leptin resistance is similar in concept to insulin resistance: there is an excess of leptin in the bloodstream, but the cells are no longer responding effectively. Ideally, leptin levels should fall within a functional range; for example, Dr. Bindiya Gandhi, a guest on my podcast, mentioned that she likes to see leptin levels between 7 and 10.

Common causes of leptin resistance include:

✔️A standard American diet high in processed foods and refined sugars

✔️Chronic psychological or physiological stress

✔️Sedentary lifestyle

✔️Poor sleep quality

✔️Systemic inflammation

✔️Inflammation, in particular, plays a central role in disrupting leptin signaling.

Leptin and Thyroid Health

In a 2013 article I wrote titled "The Role of Leptin in Thyroid Health," I referenced research linking leptin to both obesity and thyroid autoimmunity. One study proposed that leptin may act as a key mediator between obesity and autoimmune thyroid disease such as Hashimoto’s or Graves’ disease.¹⁰

While thyroid hormones influence nearly every tissue in the body, current literature does not show a direct or consistent relationship between thyroid hormone levels and leptin resistance.

How to Overcome Leptin Resistance

The good news is that leptin resistance is often reversible with targeted diet and lifestyle interventions. Here are some effective strategies:

Eat a nutrient-dense, whole foods diet. Focus on high-fiber vegetables, quality protein, healthy fats, and minimize processed foods and added sugars.

Prioritize regular physical activity. Both aerobic exercise and resistance training have been shown to help regulate leptin and improve sensitivity.

Get sufficient, high-quality sleep. Poor sleep is a known contributor to leptin resistance and increased appetite. Aim for at least 7–8 hours per night.

Manage stress levels. Chronic stress elevates cortisol and inflammation, both of which can impair leptin signaling. Incorporate stress management techniques such as deep breathing, meditation, or gentle movement (e.g., yoga or tai chi).

Reduce inflammation. Identify and address inflammatory triggers, which may include food sensitivities, gut infections, environmental toxicants, or chronic infections.

Additional Thyroid-Related Resources

Click Here for Why I Stopped Using Fluoride and How it Affects Thyroid Health

Click Here for Leptin and Thyroid Health (episode 152)

Click Here for the Role of Leptin and Thyroid Health (article)

Click Here to access hundreds of thyroid-related articles and blog posts

Click Here to join the Graves’ disease and Hashimoto’s community

Click Here to purchase one of Dr. Eric’s thyroid-related books

Click Here to work with Dr. Eric and his team

References:

Click Here to access the references

That’s a wrap