Managed EMS but increased insulin and differing test types/terms

Laura and Ero

Ero has been doing well since our barn move in December. He's on a drylot with similar-issue friends 24/7 and we're back in light to medium work after the winter. Continuing 4 week trim cycles. Hay is tested, weighed and balanced by Dr Kellon. Hay has changed but he's managed quite well, so I was surprised that his insulin jumped from 18.34 last June to 25.85 this May. Should I be concerned?

Additional background. 
--Due to barn incident last May, he had a suspect lami situation and we moved barns in June. He remained on soaked hay and was Stim tested with glucose/insulin in June. Numbers were good! He was deemed well-managed with a positive recovery protocol. Insulin was 18.34.

--Had to move closer to home in Dec, and not able to soak hay at new barn. I found tested s/s 6.0 canary grass hay, no soaking required, balanced by Dr K (U-Balance Foundation). Plus he was moving a lot more (24/7 drylot and had friends). However, after a few months he refused the canary hay, so he was switched to the new barn's round bale hay in April, s/s tested at 7.8 (also not soaked). He has not shown any metabolic symptoms outside of some recent breathing challenges (but it also got very hot here very suddenly). 

I had his blood pulled for annual glucose and insulin check last week. Insulin jumped to 25.85. Should I be concerned? 

All tests were done through Cornell and are in my CH files/folder. CH is also up to date. Current vet is not concerned given he's in the 'range', but why would insulin (and equivalent sub-numbers) go up given what I believe to be pretty ideal management? Despite low s/s hay, should I be soaking again? Blood was drawn mid-afternoon/mid 70s and humid, but he was not exercised before and had hay within 2 hours of the testing. He DID have his 8:30am flax/E/vitamins/handful of Stabul-1 though. Might that have been enough to trigger a higher insulin? Here's his May bloodwork results

In comparing prior results to this year's, a few things are different, but I don't know what they mean. Can someone help explain?
- Test type before was "serum", this time was "blood, whole, Corvac"
- Cobas Interface was "2"  this time and in previous tests is was "1" 

Ultimately, do I need to be concerned given the insulin jump? He's already fairly tightly managed and in the best place yet, but should I soak hay again to keep him managed? I'm waiting to see if his breathing issues subside before increasing work. Currently briefly wetting hay to see if it's dust related. 

Thank you for any input. 

Laura and Ero

October 2020 | Erin, WI USA 

Ero Case History

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