Thanks for putting up the case history. The ACTH of 30.7 in April is on the high side of normal at a time when ACTH is at it's lowest point. It is a jump from the last result you had in 4/11 that was 22.1. That is a red flag that things may be changing.
His insulin number has more than doubled from the 2011 number. When you plug it into the IR calculator he is compensated IR, on the cusp of being severe IR. See the formula here:
Just because the numbers fall within the lab's normal ranges does not mean things are fine. Normal does not necessarily equal healthy/fine. If it is in the finances, I would definitely suggest rechecking the ACTH in Sept. Need to get insulin/glucose/leptin to be able to see the whole picture rather than just a part of it. The relationship of the insulin to the glucose is an important puzzle piece and the leptin tells you more about what Onyx's baseline metabolism is.
A crest is a symptom of IR and is not the same as muscling changes due to working properly. An IR horse can be underweight and still have a crest. Runny eyes can be a symptom of IR. The change in shedding and the long guard hairs remaining could be PPID signs.
