Insulin spike - How soon, how long & how high?


Sheri and Peaches
 

How soon after a horse begins eating breakfast will insulin spike?  For how long does it remain elevated?  And, how much higher than normal will the insulin spike?

I consider Peaches' feeding to be "free choice," because she always has piles of rejected hay in her stall, 24 hours per day.  Every day, I take out the rejected hay.  I feed fresh, new hay at least four times per day.  The night before a blood draw, I give extra hay for dinner and again at midnight.  But rarely do I get up early enough the next morning to feed four hours before the vet arrives, especially if he shows up early. 

This morning, I went to the barn in my pajamas and found Peaches standing outside, listening to the birds and watching the sun rise - not eating any of the mountains of rejected hay in her stall.  I gave her three new flakes, which she started gobbling like a starving horse.  An hour and a half later, the vet tech arrived to draw blood.  Peaches was already done eating, having left lots of rejected hay behind.  Should I assume that her insulin results are going to be falsely elevated because of the timing?  If so, by how much?

Peaches is IR only, not PPID; taken off of Steglatro for elevated GGT; currently 30 days on 1mg Pergolide (hoping to control insulin without Steglatro); getting 1st cutting 2021 Timothy, ESC 7.2%, Starch 0.5%, Protein 10.4%, NDF 49.2%, plus minerals balanced to hay testing.  Gizmo munches the grass hay right down, so I think it's edible.  Peaches exhibited the same picky eating behavior when she was getting alfalfa, pickier now that she's on grass-only.  When I was having blood draws during the day, the blood wasn't always getting processed in a timely manner.  Now that I switched to early morning, I'm not sure the blood results are reliable because I don't get up early enough.  Real world life is not as easy as it sounds.

Thank you for your input!

--
Sheri P in IL 2021
Peaches Case History & files:  https://ecir.groups.io/g/CaseHistory/files/Sheri%20and%20Peaches


Eleanor Kellon, VMD
 

Could you post a picture of Peaches?

If she had food available to eat, she was not fasted. Picky does not triumph over hungry.

Why are you wasting all this hay instead of calculating how much she needs and putting it in nets?

Since Peaches is not PPID, pergolide will do absolutely nothing to control her insulin. What were her triglycerides?
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001
The first step to wisdom is "I don't know."


Sheri and Peaches
 

Thank you for your response. 

Peaches is on pergolide during this year's seasonal rise, because her Steglatro was discontinued for rising GGT, with normal triglycerides and equivocal ACTH.  See, https://ecir.groups.io/g/main/topic/92684672#280980

Most recent photo on my computer has been uploaded:  https://ecir.groups.io/g/CaseHistory/photo/265813/3487430?p=Created%2C%2C%2C20%2C1%2C0%2C0 and represents her current weight.  So far, her crest has remained soft while on the pergolide and off of Steglatro. 

Best regards,
Sheri

--
Sheri P in IL 2021
Peaches Case History & files:  https://ecir.groups.io/g/CaseHistory/files/Sheri%20and%20Peaches


Kirsten Rasmussen
 

Sheri, it might be helpful to post a current photo, too, from a similar angle.  Her May photo does not look to me like she has PPID, but the physical changes associated with PPID can show up fairly quickly during the seasonal rise.

--
Kirsten and Shaku (IR + PPID) - 2019
Kitimat, BC, Canada
ECIR Group Moderator
 
Shaku's Case History
Shaku's Photo Album


Kirsten Rasmussen
 
Edited

To answer your question about our 4-hour rule, here is a paper in our files that shows the insulin spike occurring during the first 4 hours after an overnight fast.  See Figure 3 for the insulin results and note that insulin returns to a steady baseline after 180-240 minutes, depending on what was fed (ie beet pulp vs oats vs orchard grass hay). 
https://ecir.groups.io/g/main/files/Glucose%20and%20insulin%20response%20to%20feeding/1-s2.0-S073708062030054X-main.pdf

This is a very interesting paper and I recommend reading it all, and studying Figure 5, too, which shows the anomalously long insulin response after a high starch meal...evidence for how prolonged and high of an effect a high starch meal (added oats) can have, and these were quarter horses (ie, unlikely to have EMS, which is consistent with their very low fasting insulin).  This is one reason to not feed grains before testing your horse for EMS: it skews the results towards false positives.

--
Kirsten and Shaku (IR + PPID) - 2019
Kitimat, BC, Canada
ECIR Group Moderator
 
Shaku's Case History
Shaku's Photo Album