Morning Nicole!
As Sienne explained insulin is a hormone and hormones are tightly controlled in the body through an intricate system involving feedback from the control centers in the brain and receptors on the glands. When the sugar level in the blood rises a signal is sent out to the beta cells to produce insulin, in the case of a diabetic who has only a few working beta cells the response is inadequate, although the few weak beta cells try thier hardest they just can't make enough to make much difference. So you inject insulin into the body it is detected by the regulating system which then STOPS sending out the message that insulin is needed and the beta cells take a break and rest while the Lantus deals with the sugar in the blood taking it into the cells (muscle, nerves) where it will be used as engery. After eating more sugar is moved into the blood from the stomache/intestines where it can be collected up by the available Lantus and carried away. During this time the feedback system is still not sending signals that insulin is needed and the beta cells continue to rest and heal and new ones grow but are not immediatly over stressed. After a while as the Lantus wears off and the sugar starts to rise the message gets sent to go to work and make insulin, as more and more healthy beta cells are present they begin responding and making endogenous insulin which lowers the sugar. Now when you shoot insulin you have a lower overall BG level because some work has been done by the natrual insulin so what you give may be to much, that's when the BG will go below 50 and you need to feed to provide something for the excess insulin to transport. Now you need to reduce your dose. This cycle contines sometimes it goes fast sometimes we reduce to soon or too much and the new fragile functioning beta cells become overwehlmed and start to fail then the BG rises and we need to supply more Lantus to help them out a little longer. Eventually if all goes well we can continue to earn these dose reductions until no more exogeneous insulin is needed and we have enough healthy working beta cells to manage the job. This is also why remaiining on healthy low carb diet even after remission is important because those new beta cells are fragile and even though many have healed we still don't have a 100% functioning pancreas like before the diabetes. If we overload the delicate system with "junk food" it won't be able to handle it and we will burn out the system.
Two (ok three) reasons why some cats don't go OTJ or why after being diabetic for a long time makes it less likely is ...#1-Although Type 2 diabetes is most common in cats (humans too) a smaller precentage of cases is caused by type 1 which is an autoimmune disease where the body produces antibodies (things that normally are used to fight "invaders" such as viruses, but it screws up and begins making antibodies that flag the beta cells as being a foriegn invader and the immune system then attacks and destroys them, this proccess continues until all beta cells are destroyed and the animal is unable to produce any insulin itself. Even if through giving exogenous insulin some new beta cells can regenerate or grow the body will just again attack and destroy them so we are helpless except to give insulin forever. #2 After being diabetic even Typ 2 for a long time sometimes the damage is too great and too much pancreatic tissue has been replaced by scar tissue which is useless and healing simply can't occur. This happens when the diabetes goes untreated or unsatifactorily treated (BG too high most of the time) for too long, the longer the BG is high (over normal) the longer and harder the feedback system keeps sending out messages to "get to work" and the harder the beta cells try but they can't and they just suffer burn-out, in addition glucose free in the blood is like poison to most cells in the body, it rots them if you will, that is why many diabetics develop neuropathy (damages nerves) and it is toxic to the beta cells further damaging them. When this happens over a longer time the damage is to great and remission is not possible. #3 which actually occurs in connection with number 2 is simply atrophy (you know "use-it-or-lose-it") After being diabetic for a while and having a lot of damage to beta cells, even if there is a few left and repair is possible, sometimes a cat has just been on insulin for so long that the feedback system has gone to sleep (it didn't have anything to do!) and the beta cells were not being stimulated at all so they too just went to sleep and begin to shrink up and dissapear. This is known as supression and atrophy, once it occurs it is often (not always) irreversible. To avoid this or to slowly "wake up" the system no matter which hormone we have neen giving, it is always recommended to taper the dosage slowly and stedily until everything is back on line and working on it's own. Stopping hormone medications suddenly is dangerous if the system is asleep and can't wake up and respond it can be life threatening leaving the body without certain hormones. This is particularly the reason why cortisone type drugs (cortisone is another hormone) are always step-wise reduced before discontinuing the drug completely.
Just as additional info. there are other forms of diabetes which you may see occasionally. Gestational diabetes occurs sometimes in pregnant women, although it can complicate the pregnancy and be dangerous for the fetus, it usually occurs late in pregancy and can be treated, it also usually goes into complete remission after the birth. This is why most women have thier BG tested several times in the 2nd and 3rd trimesters and sometimes a glucose tolerance test will be preformed if GD is suspected. Another cause of diabetes or Psuedodiabetes is caused by the disorder Cushings-syndrome which is where the body has an excess of the hormone cortisol (cortisone) cortisone works against insulin and also stimulates the release of glucose into the blood, which leads to hyperglycemia. Cushings can be caused by tumors (usually non-cancerous) of the feedback glands which overstimulate the production of cortisol, or the glands themselves (adrenal cortex) which produce the cortisol. Additionally it can be caused by giving cortison medications (usually tablets like Prednisone) in higher doses for longer periods of time (it is a potential side-effect of steriod Tx) It can generally be cured by surgery to remove the tumor or with drugs that block the pproduction of cortisol. If caused by cortisone drug stopping the medication will often lead to remission of the diabetes. If treated early then the diabetes will also go away, assuming that the beta cells were not to damaged during the hyperglycemia. Another cause is Acromelgly which is another overproduction of hormones from the stimulating system which is caused by a tumour in the pituitary (a small gland at the base of the brain) The tumor produces excess growth hormone, which in humans is called HST (human somatotropin) you have no doubt heard of BST (bovine somatotropin) which is contiversially injected into cows to make them produce more milk or grow bigger for more beef. Well when this hormone is overproduced in humans when they are small children they continue to grow very large very fast and they don't stop until it is treated, today it is rare to see these "Giants" that used to be circus preformers because the diaease is detected and treated. In adults that are already full grown when the disease begins they begin to grow larger hands and feet and sometimes the head gets bigger. The growth hormone also stimulates a thing called inulin like growth factor (IGF) which looks simular to insulin but it doesn't do the same job as insulin. It gets in the way and blocks the receptors which insulin uses to attach itself and bring the glucose from the blood into the cells. When these receptors are all plugged up by the IGF then the glucose cannot get out of the blood into the cells and hyperglycemia occurs. People or animals with disease can often be cured by having thier tumor removed or shrunk by laser etc. and the diabetes like symptoms and need for insulin will also go away. The hyperglycemia needs to be treated with insulin untill the tunor is gone and the excess IGF has cleared out of the body. Usually the dosage is very high (some cats are getting 20-50U BID!) the idea is to put so much insulin into the body that it over powers the IGF and can get the glucose into the cells. These animals have a functioning pancreas but it can't produce enough insulin to compete with all that IGF running around, so to prevent the complications of hyperglycemia insulin has to be given.
So that is probably more than you ever wanted to know, but now you understand what is going on with Baby more and what could be the situation for some of the other cats here, or even someone you meet who is diabetic. You can say "I know why that is!" and sound like a pro.
Now I have to go make lunch!
ETA: I should mention that some of things are just my theory (which many others support as well) we still don't know everything, and you know what they say about a THEORY: It takes hundreds of repititions and studies to support it and establish a theory, and just one SOB to come along and prove it all wrong! :roll:
