I have worked on both sides of the fence...CNA in high school/technical school, then to LPN, and now to RN...Remember the old saying? You catch more flies with honey than you do with salt?
When I statred out as an LPN after working there as a CNA some resentment was felt by everyone involved, because I was suddenly 'one of them'.
I agree with the above mentioned stuff, esp. the case load stuff...how many patient's does the CNA have? If the no. is around 7 or more than it may be that she truly is too busy to get it all done.
Also, do you KNOW that she is comfortable doing some of this work? She may have had a patient Vagel down during a turn and is now afraid to do turns, etc. So, take a step back, look at the big picture...is it ALWAYS the Glucose test she does not do? (fear of blood borne infc's) or ALWAYS the bath's/bed's (bad back)...If you cannot find a pattern AND it isn't patient overload then and only then would I just confront her. However, do it in a kind manner -- ask her to lunch, or carry a cake to work and establish a CNA appreciation day. It may be as simple as the CNA just doesn't feel appreciated.
This may be the case if it is a universal problem and not just a particular CNA.
If so, many times the CNA's feel like they do all the work. Our Hospital has RAD days where everyone gets dropped down a notch -- RN's do LPN work or CNA work depending on the rotation, LPN's do CNA work, CNA's do some housekeeping and some CNA's shadow RN/LPN's. It really increased teammember playing and it is not uncommon to have EVERYBODY say at any given time..."boy that CNA/LPN/RN work is tough...I'm glad I have my job and not hers"
You could try this too...have the CNA shadow you all day and the both of ya'll team work all patient care together. Maybe an appreciation of what you really do will make her more receptive to what you have to say.