When we are looking to find out whether one has autoimmune diabetes or not, in addition to testing one's insulin levels, either by testing fasting serum insulin or by using a c peptide test, which also measures insulin secretion, we also often run a GAD antibody test, to see if there are high enough levels of this antibody to indicate either type 1 or type 1.5, which is a combination of type 1 and 2 with the reduced insulin secretion of type 1 along with characteristics of type 2 such as insulin resistance.
Some think that any level of these antibodies indicate autoimmune diabetes, but GAD tends to often have some level of antibodies in some people without autoimmune diabetes as well, and you're looking for it to be over a certain number, such as over 1.5, which should be indicated on the lab report as the normal reference range.
That part is interesting though as if we do have even a sub clinical level of antibodies to GAD, this may indicate some problems with this, although to a lesser degree than the more full blown autoimmune attack we see in autoimmune diabetes.
A great many people think that in autoimmune diabetes, antibodies attack the beta cells of the pancreas and kill them off. This isn't the case at all though, they actually attack GAD although this does lead to beta cell death if GAD is under enough attack.
So what the heck is GAD anyway? Well it's full name is glutamic acid decarboxylase. So from the -ase part we can see this is an enzyme. What this enzyme does is convert glutamate to GABA, which is a neurotransmitter.
So what does reducing the conversion of a neurotransmitter have to do with diabetes and in particular, the beta cells? Well GABA plays a pretty big role in diabetes and in autoimmune diabetes as well.
So the first thing that should come to mind here is that if we have autoimmunity to GAD, then we convert less glutamate to GABA, so maybe low GABA has something to do with this. So there's actually been some studies done showing that GABA supplementation does help, in fact it was even shown to reverse type 1 diabetes in rats.
Another thing that happens with GAD under attack is that the body can have excessively high levels of glutamate, which is a toxin at high levels. Our diets are full of this stuff as well, through various forms of MSG, and there's actually a pretty long list of different things that this substance as called, like textured protein for instance, to name just one.
Glutamate is also an amino acid, so it's something we have plenty of already, and when we add additives containing free glutamic acid (another term for MSG), and when we have GAD antibodies on top of that, then levels of glutamate can get pretty high indeed.
We're not even sure of all the ramifications that excessively high glutamate has on diabetes but we do know that this is not a desirable thing at all, and is already blamed for a number of dysfunctions, including depression, especially depression when one has autoimmune diabetes. It can also cause a taurine deficiency, and that should be taken into account.
One of the things glutamate does is to elevate insulin levels, among those who do not have autoimmune diabetes, like those with type 2 for instance, or even those who don't but either have too much insulin resistance or are headed down that road, which is a very high percentage of the population actually.
Guess that opposes glutamate and gets levels under control? Well GAD converts it to GABA, but GABA itself opposes glutamate and is basically the opposite of it. GABA has even been shown to normalize insulin secretion, which makes it perfect for those of us who secrete too much, which includes obese people as well as almost all type 2 diabetics and prediabetics, although if we're not secreting enough it can increase it, which in this case is what we want.
So given that GAD antibodies may be present to some degree in type 2's as well, not to the extent that your beta cells will be killed off enough to be a type 1 or type 1.5, but keep in mind that we can have subclinical variations of anything and this might be the case with GAD, in fact it's almost certainly the case actually, as if you have antibodies than some GAD is being destroyed, and some glutamate doesn't convert to GABA, and we'd expect you to be therefore lower in GABA.
GABA is for sale as a supplement though, and it's something that I take personally, and I think that it may indeed have some benefit for at least some of us, and may be worth considering, especially if you have some level of GAD antibodies, and for that matter, even if you don't.