HA1C, glucose metabolism and thyroid

[ITHY]

What connection is there between HA1C, glucose metabolism and insulin resistance?

Thank you.

[Tina_Maria]

Thyroid hormones, and especially T3, are the drivers of our metabolism. T3 can affect glucose metabolism in a number of ways:

Insulin secretion: T3 can improve insulin secretion in hypothyroid mice.

Insulin signalling: T3 can enhance insulin signalling by increasing insulin levels in the plasma and insulin synthesis and storage in pancreatic islets.

Gene expression: T3 and glucose regulate the expression of genes that are important for β-cell maturation.

Thermogenesis: T3 and glucose can increase thermogenesis, which can lead to decreased body weight and improved glycemic levels.

So if you have a thyroid dysfunction and as a consequence low levels of T3, this can lead to an increase in glucose concentrations, as the body is not able to process the glucose effectively and therefore levels will rise.

The HbA1c is a measure of glucose concentrations over a 2-3 month period. It measures glycated haemoglobin (basically the glucose that is bound to the red blood cells) and as red blood cells renew themselves every 2-3 months, this is a good indicator of your blood glucose levels over that period of time.

A lack of T3 is also associated with insulin resistance, which means that the body becomes less responsive to the actions of insulin and over a period of time this can lead to elevated glucose concentrations and eventually to type 2 diabetes, highlighting the crucial role of T3 in regulating the metabolism at a cellular level.

Therefore it is essential to treat hypothyroidism with sufficient amounts of thyroid hormones, and especially sufficient T3, to avoid follow-on metabolic consequences of too low thyroid hormones.

[arTistapple in reply to Tina_Maria]

“So if you have a thyroid dysfunctional and as a consequence low levels of T3, this can lead to increase in glucose concentrations …….”

This question and another related question has come up on the Forum a number of times, without (as far as I am aware) such a definitive ‘partial’ answer. Some Forumites have noticed a rise in glucose levels on commencing T3. Can you therefore answer the next part of the question; is this is a temporary phenomenon and HbA1c levels return to normal at some point.

Quite a few people would like to know that I am sure.

[Tina_Maria in reply to arTistapple]

Interestingly, hyper- as well as hypothyroidism both are affecting glucose metabolism and can lead to a dysregulation of glucose homeostasis. As with all hormones, a fine balance is needed.

Large T3 doses (as seen in thyrotoxicosis) can increase glucose levels in humans. T3 can increase glucose production in the liver by activating sympathetic neurons in the hypothalamic paraventricular nucleus, it can also increase the dysregulation of liver glucose and lipid metabolism, which is characteristic of insulin resistance. Furthermore, T3 can increase the rate of glucose oxidation and decrease the glycolytic intermediate, fructose 6-phosphate (F6P) in cardiomyocytes and can also increase mitochondrial biogenesis and pyruvate transport across the mitochondrial membrane. I have attached an article on thyroid disorders and glucose metabolism:

pmc.ncbi.nlm.nih.gov/articl...

This is my own scientific conclusion, but the rise in glucose people may see after starting T3 could be due to the sudden increase in T3 after being deprived of it. In response, the body might activate pathways that respond to an 'excess T3' and this could manifest in an increase in glucose. However, as time goes by and the metabolism comes more 'in tune', the liver and other cellular pathways will become more efficient and the metabolism will be able to regulate glucose metabolism and homeostasis more effectively. So I believe that this rise in glucose will be mainly an acute response to the sudden influx of T3 at the start of therapy, and once the metabolism is more used to it and fine-tuned, the levels will normalise again. And if this was not just a temporary observation, we would see a lot of people taking T3 have elevated glucose levels, which I don't think is the case?

[arTistapple in reply to Tina_Maria]

Absolutely brilliant. Thank you. Plus I think hypothyroids with high levels of mucin which contains glucose of some sort, may be releasing previously excess glucose into the bloodstream when the body gets some T3. The body has been it’s ‘safely’ storing the glucose it can’t easily get rid of due to the low T3. Probably either before during or after ‘fatty liver syndrome’. It seems to me it’s all working on that ‘metabolic’ level.

[Capan24 in reply to Tina_Maria]

Thanks for this info. When I looked more into it I've read that T3 plays a critical role in regulating metabolism, including the way the body processes glucose. When T3 is low, it can lead to insulin resistance and impaired glucose tolerance, which might cause blood sugar levels to become unstable. I just take Synthroid daily. My doctor usually doesn't check my t3, but maybe I will ask her to. I usually just get TSH and free t4, and occasionally TPO antibodies checked. I've been noticing on my last three Labs my hemoglobin a1c has been a little bit higher than normal. This really puzzles me because I am not overweight, don't consume processed foods and too much starches, and eat a plant-based gluten-free diet. Maybe I need to take a different medication.

[Tina_Maria in reply to Capan24]

Well this is why it is so important to check the T3 levels, as they are key to a healthy metabolism, as it not just regulates glucose, but also cholesterol and other lipids, which cannot be processed properly when levels are too low.

And high levels of glucose or cholesterol in hypothyroidism are usually not a dietary issue, but a metabolic issue and can be addressed by increasing levels of T3 (and not by giving patients for example metformin or statins, when all they require is an increase in thyroid medication!).

[ITHY in reply to Tina_Maria]

Thank you everyone for the replies, thank you Tina! I have an added problem with hyperPARAthyroidism. High calcium distorts glucose metabolism.

Having had a thyroidectomy due to thyroid cancer (more than 20 years ago) makes things complicated too.

I will try T3 on a regular basis now, taking 6 µg a day to see what happens. I do not want to be insulin resistant. I am a bit worried about T3 and its effect on osteoporosis. I have -4.2,

I have a lot of digestive issues, I suspect they have to do with histamine intolerance (how to test?) There is lactose intolerance present.

[sparkly]

I think fatty liver disease was also a connection with these for me. I've hopefully reversed that now and all iffy bloods connected with everything

[Bearo]

My T3 was good for a year or so when diagnosed but has been going down ever since…..now generally between 20-40% of range.

My annual HbA1c has been 40-43 over the past few years. That puts me in the pre diabetes range.

How can I tell if the high glucose is due to low T3 or other reasons? Are there other glucose or insulin tests that would not be affected by T3?

[Tina_Maria in reply to Bearo]

There are also other factors such as genetics and family history that influence our predisposition to impaired glucose tolerance, and lifestyle and exercise can also impact on how well the body can deal with glucose in general. Insulin resistance can also occur as we get older, as the body is getting less sensitive to the action of insulin that is being secreted in response to glucose, so levels may stay high.

However, if your T3 has been consistently low (and 20-40% is not very high in range), is there a possibility that you could test your thyroid function and see, if you might need an increase in your thyroid medication? It might not be the only reason why your glucose concentrations are higher, but if you try to increase your T3 to say around 50-60% at least, you could see if that has an influence?

If you are eating a healthy diet and getting some exercise (as this helps with the processing of glucose), the other obvious factor would point to a low T3.

[Bertwills]

I’ve had problems with HbA1c tests. I take 40 mcg of T3 a day. I tried the supposed “cure” of prediabetes of eating less than 30 to 50 grams of carb a day for 6 months. Sarah Myhill insists all her clients do it. It had the opposite effect. My HbA1C went up 5 points during the six months & when I stopped low carb but still ate in a restricted way, ie gluten & dairy free it went up again 10 points.

I’m now fully diabetic & taking Sitagliptin. I’m very confused by the connection between T3 & poor suger control. I was active, 10,000 steps a day & eating well, so is it genetic?both my parents developed diabetes in their 60s.

[Mrsdeepsleap in reply to Bertwills]

Type 2 diabetes can be genetic, and isn't always due to bad diet; people of Asian or Afro-Caribbean descent are at much higher risk, even if they have a healthy diet and aren't obese. There are many things at play with both type 2 and type 1. I was diagnosed Type 1 (insulin dependent) at the age of 5, after a bout of flu; typical auto-immune response. I was only diagnosed hypothyroid last October, but noticed for a few years before diagnosis my control was all over the place, for no reason. Previously very well controlled, suddenly my sugar levels were either sky high or rock bottom, no steady line, just up and down all the time. So in my experience, yes, thyroid issues can have a huge knock on effect to your sugar levels and HbA1c. As I still haven't found that sweet spot with thyroid medication, it is too soon for me to say if things are getting better, but I am hopeful.

[Tina_Maria in reply to Bertwills]

Genetics can be a very strong influence on developing any disease, including diabetes. The predisposition can also be passed on through for example poor nutrition of the mother in pregnancy, by missing out on key nutrients, and therefore already laying the groundworks for an impaired glucose control. Add in poorly controlled hypothyroidism for a long while, and it might be very difficult to reverse this, even when you eventually get the thyroid under control.

I am sorry that you have developed diabetes, but hopefully by monitoring your glucose levels closely, getting your thyroid levels checked and adjusted accordingly and being active, you can avoid complications.