weight loss in spite of the fact that kitty has a good appetite and eats well; conversely in some cats sudden and complete loss of appetite is the only sign something's wrong
sweet breath from high blood sugar levels
oily skin (not just spiky fur, but under it as well)
Diabetes and other body processes
Feed your cat small frequent meat-based meals; all cats need this but it's critical for diabetic cats.
Make sure his/her diet has no simple carbohydrates which are converted into sugar very quickly in the body. Be vigilant about so-called low-carb foods which may not have grains, but contain potatoes, fruits, and other such high-glycemic items.
Diabetic cats sometimes need a little bit more moderately fermentable soluble fiber in their diet than their non-diabetic counterparts. 1/8 teaspoon of either rice bran (NOW and EnerG brands) OR 1/8 teaspoon psyllium husk mixed with water are good choices. If your cat won't accept either of these, low-glycemic vegetables 5% or less of overall diet works well too.
Keep honey on hand if kitty becomes hypoglycemic or starts shaking. Rub some along gums to bring blood sugar levels up.
Holistic treatment options
Use only water-soluble extract (to avoid coumarin and oils)
Avoid cinnamomum cassia form
Vitamin E - in humans has been shown to help diabetics cut back on their need for insulin e.g. as reported here. One can give cats 50-100 IU daily.
Pancreatic enzymes – if there is diagnosed Exocrine Pancreatic Insufficiency (EPI) to help the pancreas do its job. .
Pancreas glandulars and/or adrenal glandulars. Glandulars are made from animal tissue. Look for a brand that uses organic, good quality glandular material.
Water-soluble vitamins such as Vitamin B-Complex and Vitamin C. Ascorbic acid is a little rough on the stomach, so calcium ascorbate might be a better idea. In this paper, they found ascorbic acid helps with blood pressure and cardiovascular risk. Cats produce their own Vit C, but who knows, in times of stress, it's possible Vit C can help?
Trace minerals can be useful as well as chromium, zinc and manganese help to balance blood sugar. This is safer than giving Chromium Picolinate, on which even for humans, the jury is still out as to its safety and efficacy.
CoQ10 - 10mg of CoQ10 per 3 lbs of kitty body weight
These two supposedly work by increasing sensitivity of tissues to insulin and decreasing glucose release from the liver: Vanadyl Sulfate 10mg and Chromium Picolinate 200mcg
Below are 2 references (same author/presenter) that talk about using chromium (200mcg dosage) and vanadyl sulfate for cats with diabetes:
Greco DS. "Treatment of non-insulin-dependent diabetes mellitus in cats using oral hypoglycemic agents". In: Bonajura JD, ed. Current Veterinary Therapy XIII. Philadephia, PA: W.B. Saunders; 1999:350.
Greco DS. "Treatment of feline diabetes mellitus (dm) with pzi and transition metals". American Association of Feline Practitioners Fall Meeting. Nashville, TN; October 16-19, 1999.