In my experience:
(1) my PPID/IR mare's insulin/glucose would not come down until her pergolide dose was correct for her, which was not based on the ACTH numbers. I had to bump pergolide up to 1.5mg despite an ACTH in the 20s(on 1.0mg) to finally gain good control of her refractory hyperinsulinemia. It was unchartered waters, bc the bloodwork said she should be fine, right? But it worked and she's been very well controlled for several months. This may be an unorthodox approach as per the group but it's the only thing that saved my mare's life (she was hurtling toward laminitis like a bullet train).
(2) while my mare's IR was uncontrolled and dangerously high (130s insulin) I could not feed her any fat,and I mean any, no flax, no nothing. It would spike her insulin within 24 hrs. Now that her PPID is correctly treated, she can tolerate appropriate amts of fat in her diet (flax, etc). Your horse may be sensitive to the very high fat content of the "Energy" supplement you are feeding. Its a thought.
(3) Did you test leptin? If not you may be able to add it on from your ACTH blood sample that is already at Cornell (they hold it for awhile). I can't remember if leptin can be run off the purple tops for the ACTH but you might get lucky.
(4) until the insulin/glucose is under control, it won't matter how much exercise your horse gets (ie, moved to new track) b/c the insulin swings are unpredictable. My mare evented last year and was super fit but still succumbed to subclinical hoof pain (laminitis) until we started treating her like a PPID horse. My mare's normal leptin results along with her very high insulin helped support treatment for a PPID-driven hyperinsulinemia vs. primary or separate IR. That was crucial info to have when my mare's ACTH was "normal" on paper but she was still having trouble regulating her insulin.
The mods will help tighten your diet and offer much more help. This is just a few observations I had that I thought might be relevant to your case. Good luck,
Kerry in NY