Since thyroid hormones play a big role in cellular metabolism, and cellular metabolism also plays a big role in glucose regulation, thyroid hormone regulation and diabetes are linked, and pretty closely linked actually.
So I want to introduce the topic of thyroid hormone function as far as how it may apply to glucose dysregulation, in other words diabetes, to both provide an introduction to this topic as well as setting a foundation for further discussions.
First of all, you'll notice I refer to low thyroid as low thyroid hormone dysfunction, and that's because this involves more than just low hormone output from the thyroid gland, and we can have thyroid hormone dysfunction with a perfectly functioning thyroid.
That's because there's more to this than just the levels of hormones that the thyroid gland produces, mostly T4 but a little T3 as well. Doctors used to prescribe dessicated thyroid for hypothyroidism b y the way, which contains T4 and T3 in the proportions secreted by the gland, but that medication is outdated they say, and they now just prescribe synthetic T4, which isn't as effective, but we'll leave that for another day.
Anyway, doctors don't really pay attention to the link between thyroid hormones and diabetes, and they also don't pay much attention to conditions where your TSH may be perfect but you still suffer from low thyroid hormone, unless you are very lucky that is and your doctor runs a full thyroid panel and is actually familiar with this other type of thyroid function.
Almost always though, their only weapon is synthetic T4, and you don't want to be giving this to people who secrete enough T4 anyway, so it's just as well.
Just having enough T4 though is just the first step on the road to healthy thyroid metabolism, and there are two more steps involved, and each must go off without a hitch. First, we need to convert T4, which is the inactive form, to T3, which is the active form. This task is performed by the liver, and when it doesn't do it's job right, well we have low T3, which produces low thyroid hormone function because there's not enough of the active form present.
The third thing is that we can also convert too much T4 to reverse T3, which is the inactive form of T3, and it binds with cellular receptors and prevents enough of the active form of T3 from being used, so in this case you can have enough T4 and you can have enough T3 but the T3 you have isn't working well enough because it's being blocked.
This is why, in order to know what the heck is going on with thyroid hormones, you have to measure all of this stuff, T4, T3, and reverse T3.
So what happens if your thyroid function is low? Well cellular metabolism is regulated by supply and demand, and downregulating cellular metabolism, as low thyroid hormone function does, reduces how much glucose cells are willing to take in.
So this results in insulin resistance, and this even happens if you aren't a diabetic. In a study they took a group of non diabetics with low thyroid and tested their fasting blood sugar and A1C before and after treating the disorder, to see what restoring thyroid function would do to blood sugar.
Fasting blood sugar didn't change, which isn't surprising, considering that the glucose supply during fasting is lower so the fact that the demand is lower wouldn't matter much. However their A1C went down significantly from the treatment, from 5.54 to 5.34, which may not sound like much if you have had a high A1C and only went down 0.2%, but in non diabetics with normal A1Cs it's very significant.
So what happened here is that the patients' insulin resistance decreased, as their cells were more willing to take in more glucose with their thyroid balance corrected.
However, what if you are hyperthyroid, and in particular, have too much T3? It's actually the too much T3 that makes you sick here, and when it comes to blood sugar, this does its dirty work in the liver, causing it to produce too much glucose.
We already know what that can do, and have spoken about various hormones that overstimulate glucose production in the liver when the levels of the hormones are too high, like glucagon, adrenaline, cortisol, and growth hormone, so add T3 to the list, when one has too much that is.
This also causes insulin resistance, and has been shown to increase liver glucose production pretty dramatically, as the liver starts going crazy being overstimulated by all this thyroid hormone, as is the case with other hormones as well.
Needless to say, all this extra glucose raises blood sugar, and even though the cells are hungrier for glucose due to having their metabolism in overdrive from the excessive T3, the supply from the liver exceeds the demand and blood sugar goes up.
So both of these conditions, too low, and too high, affect blood sugar, and this is particularly the case in diabetics, where our glucose metabolism is already pretty messed up and the camel already has a lot of straws on its back, and thyroid disease is a pretty big straw to add to it. So this is something we need to pay attention to as well, and I'll talk more about this in future articles.