[sugarcatmom]

250 isn't so screamin' high, although the normal range for a non-diabetic is more like 50-120. Stress, infection (maybe he has a UTI?), dehydration can all be factors in bg elevation, but it's worth keeping an eye on it, especially with steroid use. Whether it turns out to be diabetes or not, I'd still highly recommend a diet change. The ingredients of the Purina One dry have way too many grains and carbohydrates for an obligate carnivore to be eating:

Ingredients
Chicken, corn gluten meal, poultry by-product meal, oat meal, brown rice, whole grain wheat, animal fat preserved with mixed-tocopherols (form of Vitamin E), wheat gluten, whole grain corn, natural flavor, dried beet pulp, calcium phosphate, potassium chloride, phosphoric acid, calcium carbonate, canola oil, soybean oil, salt, choline chloride, malted barley flour, dried cranberries, L-Lysine monohydrochloride, taurine, zinc sulfate, Vitamin E supplement, ferrous sulfate, manganese sulfate, niacin, Vitamin A supplement, calcium pantothenate, thiamine mononitrate (Vitamin B-1), copper sulfate, riboflavin supplement (Vitamin B-2), Vitamin B-12 supplement, pyridoxine hydrochloride (Vitamin B-6), folic acid, Vitamin D-3 supplement, calcium iodate, biotin, menadione sodium bisulfite complex (source of Vitamin K activity), sodium selenite.

A low-carb canned food would be sooooo much better! Something like Wellness, Nature's Variety, Merrick, or, if cost is an issue, even one of the grain-free Fancy Feast flavours. To back me up, here is a long but excellent article written by a vet regarding feline nutrition: http://www.catinfo.org/

Hoping your kitty gets to come home soon and returns to good health. Keep me updated . . .