High insulin again- metformin, mare cycles


Here we go again, only during the seasonal rise. I’d appreciate a review of the steps I’m taking to address Cayuse’s latest high insulin. Updated CH link.


On 9/11/20 I received the second very high insulin test for Cayuse in 6 months, this time 106.29 ulu/ml. I immediately started trying to syringe 13.5g of metformin twice a day, gave a ½ mg increase in pergolide and started soaking her hay longer. Soaked hay tests before I increased soaking times showed ESC of 5.9% 6.7% (two tests, same hay, soak time) and 4.9%


The results of a follow-up draw 17 days after these management changes: insulin dropped to 60.29 ulu/ml. ACTH is unchanged. 


Metformin dosing wasn’t spot-on during the 17 days until I found reusable syringes (silicone O-ring is the key) that I can operate smoothly with one hand. I know that Cayuse is now getting the full metformin dose. That didn’t happen until three days before the follow-up blood draw. We had a glitch the day before the blood draw when we missed the AM dose.


My plan has been to continue metformin, with another ½ mg increase in pergolide, and check insulin and ACTH again in the second week of November. That will be two months since we started metformin. I don’t see any way to know metformin’s role in reducing insulin, so for now I don’t plan to stop it. OTOH I’m not prepared to give metformin all credit for the insulin drop because Cayuse had a similar insulin drop in late spring without metformin. 


A new factor is that this year, for the first time, her mare cycles were noticeable and seemingly endless. When I checked hormones a few years ago, only progesterone was high. Is there any sense in rechecking hormones at this time of year? Could these high insulin tests be capturing the pattern of her estrus cycle?


Her insulin values are fluctuating in a bad way with a clear upward trend. Right now, interestingly, she looks good: body condition trim, crest smaller, bucking and playing. 

Cass, Sonoma Co., CA 2012
ECIR Group Moderator
Cayuse and Diamond Case History Folder                
Cayuse Photos                Diamond Photos 

Join main@ECIR.groups.io to automatically receive all group messages.