We hear it every day. Someone comes to us and says “I have PCOS but I am not insulin resistant”. That could be true, but sometimes the circumstances surrounding test result interpretation haven’t caught up with the context.
The OGTT and the fasting insulin lab values are largely meaningful in the context of the whole human body, and do not measure specifically what is happening at the cellular level. They measure a combination of cellular insulin resistance and pancreatic function. And in the earlier stages of PCOS, there is typically GREAT pancreatic function! This can sometimes result in what appears to be a “normal” OGTT. In addition, fasting insulin and other values are measured against what is called a “reference range”. What might not be clear is that the term “normal” is a statistical term that compares your values to those of over people. However, there are a lot of unhealthy people in the world. What does this mean? It means that the word “normal” is only a comparison to the reference range, and is tno the same the same as “healthy”.
It is precisely that “champion” pancreatic production of plentiful amounts of insulin, which happens because of insulin resistance at the cellular level, that leads to extra circulating insulin. And that extra circulating insulin is the main initiator of the hormonal meltdown that leads to downline disruption of ovulation and elevated androgen levels.
Instead of relying upon an OGTT or fasting insulin as the only measurement of cellular insulin resistance for non-diabetics with PCOS, we need to look at markers that exclude beta-cell function (that is another whole discussion, where PCOS has already progressed to frank diabetes). A useful screening to separate the markers of cellular insulin resistance is something you can do by looking at your lab values from your annual physical.
Try this:
If your IR index by this calculation is 1.0 or greater, this generally indicates cellular insulin resistance. Are you insulin resistant based upon this measure?
Please note that this calculation may not be accurate for some people of sub-Saharan African heritage due to genetic differences in TG production. In that case, an alternative method is needed.
Amisi CA. Markers of insulin resistance in Polycystic ovary syndrome women: An update – PMC: An update. World J Diabetes. 2022 Mar 15;13(3):129-149. doi: 10.4239/wjd.v13.i3.129. PMID: 35432749; PMCID: PMC8984569.
