Yes - cats with acromegaly are truly diabetic. They have high blood glucose, glucose in the urine, and need insulin therapy. Therefore they are diabetic. But there are different types of diabetes. In some patients the pancreas fails to make any insulin at all. These patients need insulin for the rest of their lives. This is called type 1 diabetes in humans. It is seen in younger people and children, and it may be an autoimmune disease. Most dogs and some cats also need life-long insulin therapy but it is not clear if it is really autoimmune in dogs or cats.
In type 2 diabetes (again, a term from human medicine) the pancreas is able to make insulin, but the insulin does not work - for a variety of reasons. This is called insulin resistance. In human medicine they will try diet, exercise, oral medications to control blood glucose, but sometimes insulin is needed. It is likely that many diabetic cats are this way - their pancreas can make insulin, but it is not enough, or it is not effective, due to insulin resistance. Insulin resistance in cats can be caused by a variety of illnesses, medications, Cushing's disease, thyroid disease, obesity, or acromegaly. If the insulin resistance is bad enough, these cats will be diabetic. They are true diabetics - but the underlying cause of the disease may not be pancreatic damage.
As you correctly state, when BG gets too high, the glucose is toxic to the pancreas. So if a cat with "type 2" diabetes is not managed aggressively to keep the BG normal, the pancreas has less chance to recover.
A cat with acromegaly is not likely to become non-diabetic (go into remission) until the acromegaly is treated. Some of our cats have gone into remission as long as 19 months after SRT, so it is possible for their pancreases to remain functional.
The Rand/Roomp protocol is specifically for cats without known concurrent disease. These cats are more likely to go into remission, and the chances are greater the better the BG is controlled. This is NOT a good protocol for an acromegaly cat.
(my note - she's referring to a question from me re:trying to keep a diabetic cat in the range of 50-120)
Acromegaly cats are highly unlikely to go into remission until their disease is treated. But they can have periods of variable insulin sensitivity, perhaps due to variable GH secretion from the tumor. It is dangerous to allow these cats to go under 100 - I would not recommend that. And there is no point. The reason to regulate a cat that tightly is to try for remission - that is not going to happen in an acromegaly cat.
(my note: some acro cats do seem to have times when the tumor switches off production and they can go into remission for a time. we've seen several have that happen here. the tumor that grows in the pituitary gland is classified as "pulsative" meaning it is not constant with its secretions.)
Many cats with diabetes (TRUE diabetes) likely can still produce insulin from the pancreas. Most of them have a concurrent disease that is treated or just goes away (or is never diagnosed) and they can then go into remission. Cats with acromegaly are an extreme example of this - they have a severe concurrent disease that causes insulin resistance. They are absolutely definitely diabetic.
Katharine F. Lunn BVMS MS PhD MRCVS DACVIM
Assistant Professor
Department of Clinical Sciences
Colorado State University
300 West Drake
Fort Collins CO 80523
970 221 4535
kathy.lunn@colostate.edu
kathylunn@me.com
