I wonder if there’s a batch problem. I’d never had this problem (usually it’s the opposite for the first 24 hours) but I opened a new box of 3 and applied the first sensor yesterday. After the warmup it was reading 9 (finger said 5.6) and then just kept going up to 15 when my finger said I was going down. I calibrated it this morning and, fingers crossed, it seems ok now. If it goes high again when I’m not (i checked with 2 different glucometers, countour next and abbot and both said I was in the 5s) I’ll ring Dexcom. Could a transmitter error cause false high readings?