I have played with Humalin-R, half-life is 3-4 hrs I believe. I would suggest taking it PWO only at 10-12 iu max.. Start low at like 4-5 iu pwo and work your way up, This is an extremely dangerous drug if you are not on top of your diet. Recommended carbs taken with each IU is 6-10, as well as protein, but carbs are ESSENTIAL or you will go hypo and possibly die. Keep researching on this subject Tom or PM me and I'll give you a few good sights on slin. I have read a ton on it and have tried it myself w/good results. just be careful.