The thyroid is one of the body’s most important metabolic regulators, influencing everything from energy levels to weight management and blood sugar balance. When thyroid function is impaired, it can have a profound impact on glucose metabolism, insulin sensitivity, and overall metabolic health.
People with hypothyroidism, Hashimoto’s thyroiditis, or even hyperthyroidism often experience blood sugar imbalances that contribute to fatigue, weight fluctuations, and increased risk for conditions like insulin resistance and diabetes. Understanding this connection is key to optimizing both thyroid and metabolic function.
How the Thyroid Regulates Blood Sugar
The thyroid produces hormones—primarily thyroxine (T4) and triiodothyronine (T3)—that regulate the body’s metabolism, including how cells utilize glucose for energy. T3, the active form of thyroid hormone, enhances insulin sensitivity and promotes glucose uptake into cells, helping to stabilize blood sugar levels.
When thyroid function is impaired:
- Hypothyroidism (low thyroid function) slows metabolism, reducing the efficiency of glucose uptake and increasing insulin resistance.
- Hyperthyroidism (overactive thyroid) accelerates metabolism, leading to unstable blood sugar levels and increased insulin demand.
Dysfunction in either direction can contribute to metabolic imbalances, emphasizing the need to address both blood sugar and thyroid health together.
Hypothyroidism, Hashimoto’s, and Insulin Resistance
Hypothyroidism, whether caused by Hashimoto’s thyroiditis (an autoimmune condition) or other factors, often leads to higher blood sugar levels and increased insulin resistance. Here’s why:
- Reduced Glucose Uptake – Low thyroid function slows cellular metabolism, decreasing the ability of cells to efficiently absorb and use glucose.
- Increased Insulin Resistance – With less glucose being absorbed, the pancreas compensates by producing more insulin, leading to higher insulin levels and, over time, insulin resistance.
- Chronic Inflammation – Hashimoto’s is an autoimmune condition that creates systemic inflammation, which further disrupts insulin signaling.
Individuals with hypothyroidism often experience fatigue, weight gain, brain fog, and sluggish digestion—all of which can be exacerbated by blood sugar dysregulation.
Hyperthyroidism and Blood Sugar Spikes
On the other end of the spectrum, hyperthyroidism (including Graves’ disease) can cause excessive thyroid hormone production, leading to:
- Increased glucose release from the liver – The body rapidly breaks down stored glycogen, raising blood sugar levels.
- Heightened insulin demand – More glucose in circulation requires more insulin, which can sometimes lead to reactive hypoglycemia (blood sugar crashes).
- Unstable energy levels – Many individuals with hyperthyroidism experience rapid fluctuations in energy, often feeling jittery or fatigued due to unstable blood sugar.
Managing blood sugar in hyperthyroidism requires stabilizing thyroid function first, as excess thyroid hormones drive metabolic instability.
Key Nutrients for Thyroid and Blood Sugar Balance
Nutrition plays a critical role in balancing both thyroid and blood sugar levels. Here are some essential nutrients to consider:
1. Iodine – Essential but Potentially Problematic
- Iodine is required for thyroid hormone production, as it is a key component of both T3 and T4.
- However, excess iodine can be problematic, especially for individuals with Hashimoto’s or autoimmune thyroid disease. Too much iodine can trigger an immune flare-up and worsen thyroid dysfunction.
- Sources: Seaweed (in moderation), iodized salt, fish, and dairy. For those with Hashimoto’s, working with a practitioner to determine the right iodine intake is crucial.
2. Selenium – The Anti-Inflammatory Thyroid Protector
- Selenium supports the conversion of T4 into active T3 and helps reduce thyroid inflammation.
- Sources: Brazil nuts, sunflower seeds, sardines, and eggs.
3. Zinc – Essential for Thyroid and Immune Function
- Zinc plays a role in T3 production and supports insulin function.
- Sources: Oysters, beef, pumpkin seeds, and lentils.
4. Magnesium & Chromium – Blood Sugar Regulators
- Magnesium improves insulin sensitivity and stabilizes blood sugar.
- Chromium helps glucose enter cells more efficiently.
- Sources: Leafy greens, nuts, seeds, and whole grains.
5. Omega-3 Fatty Acids & Antioxidants – Fighting Inflammation
- Reduce oxidative stress that contributes to both thyroid dysfunction and insulin resistance.
- Sources: Fatty fish, flaxseeds, chia seeds, and berries.
Dietary and Lifestyle Strategies
To support both thyroid and blood sugar health:
- Prioritize Protein and Healthy Fats – Reduce blood sugar spikes by including quality protein (e.g., grass-fed meats, eggs, wild-caught fish) and healthy fats (e.g., avocado, olive oil, nuts).
- Balance Carbohydrates – Avoid refined carbs and focus on fiber-rich, slow-digesting options like sweet potatoes, legumes, and quinoa.
- Limit Gluten and Dairy (If Sensitive) – These can trigger inflammation in individuals with autoimmune thyroid disease.
- Exercise Smartly – Strength training and moderate-intensity exercise improve insulin sensitivity, but excessive exercise can stress the thyroid.
- Support the Gut Microbiome – A healthy gut is essential for thyroid function and metabolic health. Include fermented foods and probiotics.
Functional Medicine Testing & Personalized Approach
If you suspect thyroid or blood sugar imbalances, consider testing:
- Thyroid Panel: TSH, Free T3, Free T4, Reverse T3, and Thyroid Antibodies (TPO, TG).
- Blood Sugar & Insulin Markers: Fasting glucose, fasting insulin, HbA1c, and C-peptide.
- Inflammatory Markers: CRP (C-reactive protein) and homocysteine.
Working with a functional medicine practitioner can help personalize nutrition, supplementation, and lifestyle changes to address both thyroid health and blood sugar regulation.
Thyroid function and blood sugar regulation are intricately connected. If you’ve been struggling with fatigue, unexplained weight changes, brain fog, or insulin resistance, it’s essential to assess your thyroid health.
By optimizing nutrient intake, balancing blood sugar, and addressing potential inflammation, you can take proactive steps toward better energy, metabolism, and long-term health.
Would you like more guidance on this topic? Consider booking a consultation to create a personalized health plan that supports both your thyroid and metabolic health.