ketones in urine

hi everyone
i just had a urine test and was told that i had ketones in my urine. i had a 3 hour fasting blood glucose test done last month in which my sugar levels were normal. I have also had my fasting blood sugar checked about 5 times in the last year and it was normal every time. What are some causes other than diabetes for ketones in the urine? I am not on any diet, I eat 3 full meals a day, drink plenty of water, etc. I am constantly tired even though I seep 8 hours a night, and I also have neuropathy in my feet and hands, mostly while I am in the bed. I thought it was caused by low levels of b12 but now i'm not so sure.
can anyone help me?!