My sugar was 308 after eating 2 Pop Tarts and a bowl of cereral. And after taking 2 metformin and 2 dexamethasone 4 mg. I start chemo tomorrow. What should I tell the nurse or oncologist? I am 68, 6ft. tall, 265 lbs. I have RA and had a triple negative tumor removed from my breast with clean margins and clean lymph nodes. The diabetes is a result of diet, overweight and lack of exercise, I think but 308 scares me. It was 289 before supper tonight. After I ate I took another round of meds.