I wouldn’t exactly say that insulin causes LDL to “clump up”, I haven’t really seen evidence of that thus far, but insulin definitely does seem to have a mechanistic role in the whole deal (I have suspicions as to how and why, but I’ll go over that some other time).
Key point is that it appears to be damaged LDL - not healthy - that leads to the formation of foam cells, and a constant onslought of this can eventually lead to athero. From what I’ve seen.
However fasting insulin, Triglyceride:HDL ratio, amount of “pattern B” LDL (small, dense LDL) all seem to track pretty well with over all system health, hsCRP can give some information on your inflammation status, and then your general work up like hba1c and so on.
Of course, also consider what you can get covered. Even just a standard lipid panel, hba1c, fasting insulin, and the rest of the normal workup can give you some good baseline information to see how youre doing. There is another article on cholesterolcode.com which goes over different types of tests and how often it reccomends you get them (at least once, every year etc) that you may find especially helpful.