Really, did I say not to re-insert the needle into the insulin to draw up more insulin into the syringe? I'll have to go rewatch the video. I don't remember that, but I have definitely done it. Just always being careful not to touch the needle to something that might contaminate it.
If the dial at the end of the pen is used, you have to attach special needles to the rubber stopper end of the pen and use them to give the shot. I don't think (although I haven't tried) that it would work to try to push the insulin into the syringe via the pen dial. You could always try it and let us know how it works.
We don't use the dial for a few reasons - one is that it is less precise (giving about 1u rather than exactly to the center of the syringe black line, as a random example) than using syringes. The variations of fat or skinny doses don't matter much when you're giving larger doses like people need. These insulins (Lantus and Lev) were both developed for people. But a fat or skinny dose on 1u can make a huge difference to a small cat.
A second reason is that if one is using the pen dialing mechanism, it needs to be at room temperature. That's why the recommendation to keep the pens at room temp - the mechanism dispenses more accurately at room temp than cold. But using insulin with cats you want it to last as long as possible - so we refrigerate.
The third reason off the top of my head has to do with dosing. Our guidelines have dosing in 0.25u -0.5u increments, which can't be obtained using the dial and pen needles.
You can use a syringe to try to withdraw the bubble from a pen if it's bugging you. It probably doesn't hurt anything to have it in the insulin. The vacuum that seems to exist in new pens goes away once you've used the pen for a little while.
As far as bubbles go - some syringes are far worse at creating bubbles than others. It may be more a syringe issue than an insulin issue. Unfortunately the Terumos that were such good syringes, and cheap as well, are no longer being made in the size we use for cats. They were great at not causing bubbles. I'd try a different brand and see how it works. There is a pretty good selection of needles to choose from on
www.americandiabeteswholesale.com Somewhere on this site there is a shopping button and a percentage of your purchase supports FDMB if you use that shopping link. I don't know where it is anymore, however.
A separate issue, but one that we are aware of, is that the markings on syringes tend to not be very accurate. What that means is that the markings are stamped onto the syringes, and they don't always line up at the same point. That can make your dose vary. Many people still use them - I did - because punkin was a high dose cat and I didn't think a small variance would matter too much. But for those whose cats are on small doses, or very sensitive to insulin, or who want to increase their accuracy, that small difference can matter. Some choose to use calipers, which are like external rulers. There is a post about Dosing With Calipers on the "
Where Can I Find?" thread in the second half, if any of you are interested.
So, here is a big THANK YOU from me and so many others! 
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