High blood sugar Reno

Patient: I was recently diagnosed with high blood sugar (288). The lowest I have got it down to is (143). I have changed my diet Lots of water.No pasta,lots of vegetables, no sweet drinks, but it seems to be high still. I have never been a big fan of sugar or sweets or pastas. I do like meat. I am over weight (340 lbs).I for the life of me can;t figure out why my blood sugar is so high. Hopefully you will have some idea.