yes, as leb says, it can cause insulin resistance - Sugar level disturbance is one of the side effects, which means firstly that anyone with existing problems really shouldnt have it at all, without being monitored very closely, and secondly it means that some of the population will develop this problem, like you, not having had any known history of it before. However, this does not mean you will get full blown diabetes, so dont panic yet.
I also had some fluctuations with blood sugar, i havent mentioned it on this forum before, because, for me, it wasnt a big deal, i bought a monitor so i could sort it out myself without going to the doctor. my blood Sugar is fine now, though i am overweight so i could be at risk of diabetes, therefore i stick to a pretty much unprocessed diet to keep myself healthy.
this is what i would suggest:-
No.1 get mirena out of you and give yourself time to recover, it can take a few months for the body to settle down after mirena removal.
No.2 help your body recover by being really careful on your diet,lots of water, no caffeine (which also can raise your Sugar levels), no smoking, no sugar or processed foods, especially white carbos like white bread, pasta etc. make sure everything is wholemeal unprocessed, which will help your body deal better with the natural sugars in the food. Take Chromium picolinate which you should be able to get in your health store. Chromium is a natural supplement (taken in the morning and at night on an empty stomach) which can help your Glucose Tolerance Factor and has been used by early stage diabetics to help reverse the symptoms. Get plenty of excercise in the form of walking - at least half hour a day, and if you have time, do that twice a day. You could also consider taking a medium dose B vitamin complex tablet (taken after food with water)
No.3 get yourself an electronic blood glucose monitor - they dont cost much at all - and that way, you can monitor your blood every morning to give you an idea what your body is doing.
You should find that the blood sugar gradually gets back to within normal range, and once the mirena is really out of your system in a few months, there is no reason why you should ever have any more problems with your blood sugar, if you continue to be reasonably careful with your diet.
Good luck, whatever you decide to do! There is light at the end of the tunnel, if you make the right choices, just remember that!!:) xx
ps - the other symptoms you have are also side effects of mirena, though blood sugar fluctuations can also cause tiredness and crabbiness etc, either way, mirena will be at the bottom of it.