Lol, actually carl does! But it will have to wait till later when I can type with more than one finger... simply put, ALL food will raise BG, even zero carb food. And it should take 60-90 minutes to do so unless it is a liquid sugar like honey or karo or gravy which go straight thru the tummy to the small intestine.
Carl
OK, when I saw Sue's message, I asked myself "hey, how the heck does a cat's digestive system work anyway? where do the carbs go, and what makes the numbers go up?" All I heard was "uh, I dunno.." So I used everyone's favorite search engine and googled it!
After I followed a half dozen links, I found this jewel on page two or three on the "hit list".
http://maxshouse.com/feline_nutrition.htm Totally awesome site! Told me stuff I already knew in part, but learned a helluva lot. Some of it is over my head scientific and will require a 2nd or 4th look, but here's some good info:
Cats gulp their food, don't chew it much. Turns out that is because of the way their jaw works and their teeth are shaped. They have no side-to-side movement in their jaw, just up and down. And no really flat teeth, so they can't mush the food up in their mouths like people can, so just chew enough to get it down, and then the tummy takes over. Not really important to this discussion, but I found it pretty interesting!
Cats, like all animals, require six classes of nutrients: water, energy, protein, essential fatty acids, minerals, and vitamins. Cats do not have a dietary requirement for carbohydrates. The metabolic requirement for glucose in the cat is derived from protein (glucogenic amino acids) and fat (glycerol). Cats are adapted to a protein- fat-rich, carbohydrate-poor diet.
All animals have a metabolic requirement for glucose. Carnivores, such as the cat, convert glucogenic amino acids and glycerol to glucose for the maintenance of blood glucose, and therefore, have no established dietary requirement for carbohydrates.
In general, an absence of dietary carbohydrate in the feline diet will not affect blood glucose levels or cause an energy deficiency; this is because the body can use protein and the glycerol portion of fat for glucose production, and fat and protein for energy.
So, cats require NO carbs in order to survive. That doesn't mean we should all feed zero carb food, just that carbs are pointless to a kitty. They get all the glucose they need by converting protein or fat into sugars. That is what I meant (having just read this site) about ANY food is going to raise BG. When they digest their food, which takes place in the small intestine, there are enzymes there that turn protein and fat into "sugar", which then goes into their bloodstream. Normally, the pancreas would counteract that sugar by producing sufficient insulin. In a non-diabetic cat, since their system is working normally, you'd probably not see a noticeable increase in BG after eating, because the pancreas would be there in time to offset the increase. Make sense?
So then I thought "well, assuming there are some carbs in the food, where do those go? Do they just go straight to the bloodstream and make the BG go sky high?
Carbohydrates are nearly absent in the cat's natural diet. The cat obtains small amounts of carbohydrate through the stomach and intestines of her prey. Commercial dry foods, however, may contain as much as 45% - 50% carbohydrates. Since the cat metabolizes primarily fat and protein for energy, most of the excess carbohydrate is stored in the body as glycogen and fat. The primary adverse effect of excess carbohydrate is obesity. The effects of obesity are heart disease because of the increased workload on the heart; orthopedic problems are increased because of increased physical stress on the frame, leading to arthritis and early debilitation; diabetes mellitus, a condition in which the pancreas doesn't produce the amount of insulin that it should to help metabolize blood sugar, is one of the most common problems in obese cats; several liver disorders occur more frequently in overweight cats. Surprisingly, the deadliest one, hepatic lipidosis, happens when the cat stops eating. Changes in the operation of the liver cause fat to be deposited there, which eventually can shut down the liver altogether.
This next part is a little techy and contains words I can't pronounce, but bottom line is the last line....excess carbs go not only into the bloodstream, but are primarily stored as "fats".... Which kitty can then use for energy. A starving animal, for instance, will first utilize excess fat for survival, and when the fat is all gone, then they start consuming muscle, which should come as no surprise to sugarkitty beans, because we've seen how they quickly lose weight, sometimes even muscle mass, even though they are eating like pigs, due to the fact that their digestive system is all screwed up because their pancreas (among other organs) isn't working right.
In the cat's liver, gluconeogenic amino acids and fat in the diet are deaminated and converted to glucose for the maintenance of blood glucose levels. The cat has evolved to maintain normal blood glucose levels and health on a carbohydrate-free diet, a capacity inherited from her desert-dwelling ancestors. This ability is related to its different pattern of gluconeogenesis. In most animals, maximal gluconeogenesis for the maintenance of blood glucose levels occurs during the postabsorptive state, when dietary soluble carbohydrate is no longer available. However, carnivorous species, such as the cat, are similar to ruminant species in that they maintain a constant state of gluconeogenesis - the immediate use of gluconeogenic amino acids for the maintenance of blood glucose levels (these mechanisms are turned "on" and "off" in other animals).
There are differences between cats and omnivores in the relative importance of various gluconeogenic and carbohydrate-metabolizing pathways. Compared with omnivorous species, the cat has a high hepatic activity of the enzyme serine-pyruvate aminotransferase and low activity of the enzyme serine dehydratase. Thus the cat is able to convert the amino acid serine to glucose by a route that does not involve either pyruvate or serine dehydratase.
After glucose is absorbed into the body, it must be phosphorylated to glucose-6-phosphate before it can be metabolized. The liver of most omnivorous animals, including the domestic dog, has two enzymes that catalyze this reaction, glucokinase and hexokinase. Hexokinase is active when low levels of glucose are delivered to the liver, and glucokinase operates whenever the liver receives a large load of glucose from the portal vein. The feline liver has active hexokinase but does not have active glucokinase. Consequently, the rate of glucose metabolism in the liver of the cat cannot increase in response to high levels of soluble carbohydrate in the diet to the same degree as the rate in the liver of a species possessing both enzymes. Thus most of the carbohydrate in dry food ingested by the cat is converted and stored as fat.
The site also contains a great deal of information about dry vs. wet food, and how water consumption is affected depending on what Fluffy is eating. It says that a canned food diet supplies 95% of all the water a cat needs, which is why most people see a huge drop off in "kitty at the water bowl" when they switch and ditch the dry food. Bob almost never touches the water bowl anymore. Conversely, an all dry diet only supplies only 4% of their required water intake.
When fed canned food (80% moisture) with access to drinking water, cats obtain over 90% of their total water intake from the diet, whereas on dry food, 96% of the total water intake is obtained by drinking.
And the more calories they eat from all canned food, the less water they will need.
Canned diets contain enough water that cats consuming them rarely need to drink. Daily water needs, in milliliters, often are "guesstimated" as equal to the metabolizable energy requirement in kilocalories or approximately 60 ml/kg. Once the diet is consumed, oxidation of nutrients produces an additional 10 to 13 grams of water for each 100 kcal of metabolizable energy. Thus a 4 kg cat consuming a 240 kcal canned diet containing 78% moisture will consume 237 ml or 98% of its daily water need directly from the diet. Thus the cat needs to drink less than 1 oz. of additional water per day whereas a cat consuming a 240 kcal dry diet needs to drink over 7 oz. of water per day. This can be difficult becausecats are not naturally big drinkers. Feeding a canned diet containing 78% moisture virtually guarantees homeostatic control of water balance in the cat.
I didn't even quote 5% of the page here. There's a ton of nutritional information, like how to calculate fat/protein/carb percentages, what the vitamin requirements are, and why they need them... I could spend days reading it!
And last but not least, if the question "time to get from the food bowl to the litter box?" is ever the question on Final Jeopardy, the correct answer would be "What is 20 hours, Alex"!
From the small intestine, the food passes into the large intestine, which absorbs additional nutrients and also a substantial amount of the water remaining in the ingested food. The large intestine serves as a storage area for the solid material that is left over after the digestive process. This material--the feces--is eventually excreted from the cat's body, through its rectum and anus. This process normally takes about 20 hours in an adult cat.
OK, school is OUT!
Carl
It's a good time to remember to breathe, and test again in 20-30 minutes just to be sure and aware. No need to worry or panic. Even if he does drop lower, you know there are things to do to ease him back up again (gravy, karo, etc.). Remember, it takes food a bit to show in the bloodstream, and as we're sitting here fretting, it's making it's way there. 
