Do I have a blood abnormality or disease? Sugar levels gone haywire.?

I was feeling really shakey and weak, I had one of those home blood test kits. My first reading was 23.4 mmol/l. 30 minutes after eating it was 33+ mmol/l, now around an hour later its 2.0mmol/l. Is my meter broken? How can I go from that high to that low? I stopped being shakey after eating a sandwich, is there something wrong with me or is the meter broken or is it a normal symptom of being hungry.