The Hypothyroid Series Part 3: the Relationship Between Insulin and Thyroid Function

Posted by Dr.Kirti Deol



If you have read all my past articles on thyroid health, you likely already know the importance of it’s function and how stress can be a huge contributor to hypothyroidism. 

In this blog post, I wanted to discuss the importance of blood sugar regulation and proper thyroid function. I just want to clarify, when I talk about insulin and blood sugar regulation regarding thyroid function, it does not just apply to patients with diabetes. However, the prevalence of patients with thyroid disease and diabetes, obesity, and metabolic syndrome is significantly higher than that in the general population. Minor sugar spikes throughout the day, in a patient who is not diabetic, can contribute to an under- or over-functioning thyroid and I will explain why!

Thyroid hormones play a tremendous role in regulating energy balance, metabolism of glucose, and lipids. They are involved in glucose transport and glycolysis, meaning they facilitate the disposal and utilization of sugars in peripheral tissues.

A thyroid that is not functioning properly may be the first alarm sign for a patient that is becoming insulin sensitive. The thyroid is doing all the work to keep those insulin levels down, and if continued, you are on your way to diabetic land ☹. And vice versa!

High blood sugar and even low blood sugar can affect thyroid function.

High blood sugar, simply stated, is caused usually by a high intake of carbohydrates.

When that happens, your pancreas secretes insulin to move that extra glucose from the blood in the cells where they can be utilized as energy, which is GOOD! Over time, chronically high sugar levels (ie. high carbohydrate intake) can cause the cells to lose the ability to respond to insulin. Then the pancreas gets angry and starts secreting more insulin to compensate for the high sugar levels in the blood, but no one is responding, which eventually causes insulin resistance. These repeated insulin spikes increase the destruction of the thyroid gland in people with autoimmune thyroid disease (Grave’s disease or Hashimoto’s). The destruction of the thyroid causes the thyroid hormone production to fall.

With chronically low blood sugar, a different mechanism is described to explain its relation to the thyroid gland. Now when you are “hangry” (aka hungry and angry) your blood sugar drops low to notify your brain to go into “survival mode,” which can cause symptoms of anxiety, heart palpitations, fainting, dizziness, seizures, coma, and death, if severe. Your adrenal glands also respond by increasing output of cortisol, which tells your liver to produce more glucose, bringing blood sugar levels back to normal. The function of cortisol is crucial for its ability to increase the amount of glucose available to the brain, helps with tissue repair but it also blunts other functions that are nonessential in “survival mode,” such as digestion, reproduction, and growth. This repeated cortisol release caused by episodes of low blood sugar suppress pituitary function. As I mentioned before in my past article, without proper pituitary function, your thyroid can’t function properly.

If these imbalances in blood sugar levels are not corrected, whatever you do to fix your thyroid likely won’t work! It can also weaken and cause imbalances in our gut, brain, hormones, adrenal glands, detoxification pathways and metabolism, which are all also detrimental to thyroid health.

Thyroid disease itself can also cause issues with sugar regulation and metabolic syndrome (obesity, high cholesterol, high blood pressure, and insulin resistance). A low functioning thyroid can slow the rate of glucose uptake by cells, decrease the absorption of glucose in the gut and can slow the response of insulin to high blood sugar and decrease the disposal of insulin from the blood. So basically, when you have hypothyroidism, your cell’s are not very sensitive to glucose, telling your body that your are hypoglycemic, even though you may have normal levels of glucose in your blood. Common symptoms are fatigue, irritability, angry, headache, etc. If your cells are not getting enough glucose, “survival mode” kicks in again, and your adrenal glands release cortisol to increase the amount of glucose in the blood. Then a chronic stress response occurs that suppresses pituitary function (mentioned above), which worsens hypothyroidism. As you can see, it’s a viscous cycle!

Treating thyroid disease has become a therapeutic strategy to treat diabetes and metabolic syndrome. It is important to understand that if you have any issues with blood sugar regulation, you likely have some degree of insulin resistance. Like I said, this article does not just apply to patients with diagnosed diabetes and metabolic syndrome. I just want to mention a common condition that is grossly overlooked by most physicians and is an important issue to diagnose or rule out if you are presenting with hypothyroid symptoms. Reactive hypoglycemia can cause the body to secrete more insulin in response to a high carbohydrate meal, causing blood sugar levels to drop below normal. This presents as symptoms of hypoglycemia (stated above) and can cause thyroid irregularities as well. That is another topic to discuss another day!

SO…basically it is important to keep your blood sugar in a healthy range.

How to know your blood sugar is in a healthy range? Lab testing for fasting glucose levels and Hb1Ac (marker for diabetes) can predict any issues regarding blood sugar regulation.

Two markers can be done, in the comfort of your own home with a blood glucose meter. It is the simplest, most cost-effective way to gauge your blood sugar regulation. First, measure your fasting blood glucose, which is a measure of your blood sugar first thing in the morning before eating or drinking. The second is your post-prandial blood glucose, which is blood sugar 1-2 hours after a meal. This has been shown to be the most accurate predictor of future diabetic complications and usually the first marker (before lab testing) to indicate blood sugar irregularities. Normal ranges are typically given when you buy the blood glucose meter or you can discuss these values with your physician to determine if there is any issue.

Whether you are hypoglycemic or hyperglycemic, you want to adjust your diet and lifestyle to promote a healthy glucose range throughout the day. Depending on your case, you may need to restrict your carbohydrate intake or increase it to compensate for your blood sugar issues. Through the use of dietary and lifestyle changes, herbs to increase the ability to make cells more sensitive to glucose, or supplements to help support hyper/hypoglycemia or thyroid function or a combination can be recommended to help regulate your insulin levels and in turn support the functioning of your thyroid.

Contact us or come in if you have any questions or comments about your thyroid disease or blood sugar imbalances. We are here to help find out all the factors that could be contributing to your illness!