Let's look at how to draw insulin using a syringe. If you're using a clear insulin, you can go on to the information about drawing it from the vial, but if your insulin is a cloudy one, it needs to be resuspended before you can work with it.
Before each use, take a moment to inspect the insulin prior to drawing it into the syringe; clear insulins should appear not discolored and clear; suspended insulins should be uniform in their cloudiness. 
Do not use the insulin if:
See Insulin problems for more information about "bad" insulin.
Removing the cap and preparing the syringe.
|Remove the needle cap and pull the plunger down to the number of units you intend to inject.|
You want the amount of "air units" to equal the amount of insulin units you'll be drawing from the vial.
Piercing the insulin vial's rubber stopper with the needle.
|Push the needle through the insulin vial's rubber stopper.|
Inserting the needle all the way into the vial makes it less easy to bend. 
If you should bend a needle while drawing insulin, discard the syringe and start again; don't try to straighten it out. 
Turn them both upside-down.
|Turn the insulin vial with the syringe still stuck into it upside-down.|
Look for bubbles.
|If you find bubbles, push the entire amount of insulin in the syringe back into the vial and start from step five again.
If you do get air bubbles into the syringe, it's ok with most insulins to re-inject the insulin into the vial and draw again until the air is gone.  Check that this is ok with your insulin. See also injecting insulin. Slower draw is less likely to draw bubbles.
From WebMD: 
"If you notice an air bubble inside the syringe, draw a little extra insulin into the tube. Then, remove the needle from the bottle and hold the syringe-needle apparatus with the needle pointing toward the ceiling. Tap or flick the insulin syringe until the air bubble rises, and then push the plunger to force the air out of the syringe and get rid of any extra insulin."
Some tips from Ed Bryant at National Federation for the Blind, who draws his own insulin.
"How to Get Air Bubbles Out of an Insulin Syringe 
"There are techniques by which a blind diabetic may draw and mix insulin without drawing air into the syringe. Like many others, I have used them successfully for years. I first draw four or five units of regular insulin into the syringe and then inject all of it back into the vial. I then repeat the operation two more times. The fourth time, I draw the full amount of insulin needed from the first vial. Then, when I draw insulin from the second vial, I draw the exact amount needed. I have put this to the test; 100 repetitions without air bubbles. Diabetes Action Network former First Vice President Janet Lee twice performed the same test. In both cases the complete absence of air in the syringe was independently verified."
One way way to get rid of syringe air bubbles is to hold the syringe upright and give it a tap or two with your finger . The problem with having air bubbles in the injection is that you will not be getting the full dose of insulin; the bubbles take the place of it. 
Some people prefer to gently jiggle their vials to make any air bubbles rise to the top, away from where the needle will draw.
Remove the syringe from the vial and put the needle cap back on the syringe; you're now ready to give an insulin shot.
- ↑ Insulin Therapy-Stability & Storage. RxEd.org.
- ↑ Keeping an Eye on Your Insulin. Diabetes Health (2001).
- ↑ Benson EA, Benson JW Jr, Fredlund PN, Mecklenburg RS, Metz R. (1988). Flocculation & Loss of Potency of Human NPH Insulin. Diabetes Care-American Diabetes Association.
- ↑ Playán J, Acha J, Navarro H, Sanz A, Guallar AM, Albero R. (1994). Flocculation of NPH Insulin. Revista Clinica Espanola-(English Translation).
- ↑ 5.0 5.1 Rosskamp, Ralf H., Park, Glen (1998). Long-Acting Insulin Analogs. Journal-Diabetes.org.
- ↑ Definition of Flocculation. Dorlands Medical Dictionary.
- ↑ 7.0 7.1 Storage & Safety-Frosting of NPH, Lente, Ultralente Insulins-Page 5. Diabetes Forecast-American Diabetes Association (2006).
- ↑ Humalog & Heat. Diabetesnet.
- ↑ 9.0 9.1 9.2 Injecting Insulin-Transcript of American Diabetes Association Videotape. American Diabetes Association (2003).
- ↑ Diabetes Mellitus. Washington State University.
- ↑ Giving A Dog Insulin #7. WebMD.
- ↑ Blind Diabetics Can Draw Insulin Safely. National Federation for the Blind.
- ↑ How to Get Air Bubbles Out of Vetsulin (or any insulin). eHow.
- ↑ Insulin Administration. American Diabetes Association (2002).