When patients do not shake there NPH insulin pen before injecting, they will most likely see a wide variation in their insulin levels and blood sugar control, researchers report. NPH insulin comes as an insoluble mixture of crystals and liquid and must be re-suspended before injection. So researchers in Italy wanted to know what difference it would make if patients didn’t re-suspend their NPH insulin by tipping the insulin pen 20 times before injection, and if they didn’t shake it by tipping it back and forth, whether it would matter how they held the needle during the injection. What they found was everything mattered. Dr. Geremia B. Bolli, one of the researchers, was surprised by “the high variability of effects on lowering of blood glucose depending as to whether the NPH pen is properly re-suspended by shaking or not, and (if it’s not re-suspended), even great differences depending on the position of the pen, i.e., horizontal, vertical with tip up or down.” He added that, “The same NPH appears as a different insulin in each of these conditions.”  So, when you compare with re-suspending NPH insulin, not shaking the pen before injecting could result in lower insulin levels in the blood (if you inject with the needle flat or pointing up) or higher insulin levels (if you inject with the needle facing down).  They also detected that your body would also feel the effects of insulin earlier if you injected with the needle down without shaking it first or later if you injected it flat or needle up without shaking it first.  This could result in your blood sugar rising above desired levels sooner (needle flat or pointed up) or later (needle pointed down) when you don’t re-suspend the NPH insulin by shaking the pen first. If not re-suspended, that insulin levels could vary by as much as 23% and blood sugar control could vary by as much as 62% depending on whether NPH insulin is shaken before injecting or not.  So it may seem small, but it is very important that your patients are aware of this problem if they do not shake their NPH insulin. This is also a reason to use long-acting insulin rather than NPH.  So consider this when deciding the best treatment for your patients.  Diabetes Care, online