When mixed insulin sits for a while the cloudy insulin separates and resuspension (mixing) is needed before injecting. If you use a cloudy insulin in an insulin pen, you will need to roll and tip your pen a least 20 times to get the insulin evenly mixed. Insulin in traditional vials (not pens) appears to be easier to mix and may not need 20 cycles. But be sure to look at your vial and make sure it is evenly cloudy before injecting it. If you do not mix your insulin properly you could easily be giving your self too much or too little insulin.
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