Auto cover needles

I have been using auto cover needles for three years now and sinces using them I have had DKA every year the last time I had DKA July 2011 I almosted died my insulin was increased and I am now on 40 units of nova rapid 3 times a day and 60 units of levamir at night my bloods sugars have never been below 15 and always got key tones. Three weeks ago I suggested to my consultant trying a different needle and since I have changed over my blood sugars have been very low I am having a hypo every time I take my injection up to five hypos a day this suggest to me the auto cover needles wasn't working would like to know if anyone else has had this problem? Also I'm unsure what to do next I have seen my diabetic nurse who has lowered my night insulin to 56 units but this has made no difference and I'm still having a lot of Hypos waking up at four in the morning coz my bloods have dropped to 2.4. I am not seeing the diabetic nurse for another week and can't carry on like this should I lower my insulin myself??? Any help I would be thankful for.