Has your horse actually been diagnosed as IR? If so, the most critical thing you can do is get his diet under control (low NSCs--non-structural carbohydrates). I have a profoundly insulin resistant pony and this literally saved her life. Once I started testing her hay and only buying low-sugar hay we didn't need anything other than vitamins and minerals to balance the hay (I also added flax seed and because she also has Cushing's she is on Pergolide). I can't tell you how much money I needlessly spent on supplements and any other product marketed for IR horses before I learned the key is the diet. Wish I would have saved all that money! (That being said I don't know anything about this supplement. You could check the Yahoo Cushing's group to see if they mention it. Many of the people in that group have both IR/Cushing's horses.)
If you try it please let us know what you think. Good luck.
