As most of us know, proper dietary support of diabetes mellitus is very important in overall diabetes management. In cats, diabetes mellitus can actually be reversed if there has not been too much permanent pancreatic damage and if blood sugar can be regulated quickly, the cat can become normal. For most diabetic cats, a low carbohydrate/high protein approach is the best route to accomplishing this goal.
Cats become diabetic when they experience sustained high blood sugar levels for too long. Genetics and diet aside, any cat can be made into a diabetic cat by subjecting the cat to repeated intravenous glucose infusions for a long enough time. Too much glucose in the bloodstream over time depletes the pancreas of insulin as the pancreas struggles to control all that sugar day after day. This struggle eventually creates an insulin deficiency, which is basically what diabetes mellitus is.
In a more natural setting where repeated intravenous glucose infusions do not occur, the problem is a high carbohydrate diet. When we eat carbohydrates and they enter our bodies, there is a rise in blood sugar level that persists for several hours. In the cat, it is more like 8-12 hours, even longer if the cat is obese. All this circulating blood sugar stimulates insulin secretion so that all sugar can be stored in the body. If the cat is snacking on dry food throughout the day, he or she may be secreting insulin throughout the day as well. This makes for a fat cat and a depleted pancreas.
Over-eating high carbohydrate diets promotes development of diabetes mellitus and creates obesity. Obesity itself further promotes development of diabetes mellitus.
Fat cat walking
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We have mentioned that a diabetic cat can become normal if blood sugar levels are returned to normal and kept normal for a long enough time. This cannot usually be done without insulin injections but diet is important as well.
We need to minimize the post-meal glucose tide that contributed to the cat's diabetes. One way to do this is to provide few dietary carbohydrates. The body still needs sugars to run its metabolism, but the patient's liver is happy to make them from dietary proteins and the liver does so without creating any post-meal glucose spikes. This makes for a more even blood sugar level throughout the day and reduces the amount of insulin needed to keep things under control. Sounds great, right?
So How Much Carbohydrate Should we be Looking for?
The bad news is that the information we are looking for is probably not going to be on the pet food label. We are going to have to look it up on the company website.
We are looking for less than 7% of the diet's metabolizable energy as carbohydrate
What does this mean? Let's start with "metabolizable energy." A calorie is a measurement of the energy content in an amount of food. We need this energy to run our bodies. Picture a plate of food. That food is said to have a certain number of calories. If you take the food and incinerate it, the amount of heat it generates is measured in calories. This measurement is the gross energy of the food. This is what is meant when a cookie is said to have 100 calories or a frozen dinner has 300 calories, etc.
But these calories are not 100% available to for your personal use when you eat that plate of food. Some of that food will end up as fecal matter and some calories are used in the process of digesting the food. This means that the 100-calorie cookie you ate might only provide your body with 90 calories for your personal use. The gross energy minus the energy that wasn't digested = digestible energy.
It turns out there is another level before we are able to use our meal calories. We have to process the fuel/food/calories after they have been absorbed into our bodies. We have to transport them into our cells so they can be used. After all the energy used in processing new fuel/calories is taken into consideration, we are left with metabolizable energy, a common reference in nutrition when evaluating diet. The metabolizable energy is now available to be burned/used so theoretically our 100-calorie cookie on the plate has provided us with 80 calories to actually use.
It is the metabolizable energy that concerns us because this is the only way to compare the protein, fat and carbohydrate content of different diets; we have to factor out all the undigestible or unusable material to be able to compare. Values are expressed as "% ME," in other words, the percentage of the total metabolizable energy.
Once again, the "magic number" for a diabetic cat's diet is less than 7% carbohydrate ME
Finding this information is a little trickier as it will not be on the pet food label. If you are lucky, you can go to the manufacturer’s website and find the %ME for fat, carbohydrate and protein. If it isn't available and you still want to know, there will be math involved.
Kibble requires a certain carbohydrate content to be molded and shaped but canned diets do not have such limitations, which means that this degree of carbohydrate restriction is only possible in a canned diet. There are several therapeutic diets manufactured with carbohydrate restriction fitting the above guideline. Ask your veterinarian for guidance in selection.
If possible, 3-4 small meals should be provided daily but if this is impractical, then twice daily feedings in conjunction with giving insulin can be provided.
There are many cats who simply do not like canned food and such diabetic cats can most certainly be regulated with carbohydrate-restricted dry foods if necessary but, if possible, they should transition to canned food.
Obese Diabetic Cats
Obesity makes for difficult diabetic regulation. Weight loss is key and the high protein/low carbohydrate strategy discussed above may have too many calories for an overweight cat. This is where it may be more important to use a different strategy in reducing post-feeding glucose tides. Instead of using low carbohydrate diets and forcing the patient to make their own carbohydrate, it may be better to use fiber (complex carbohydrates) to create a better sense of fullness after a lower calorie meal.
Weight loss improves the ability to achieve diabetic regulation 13-fold but must be done smartly as a greater than 2% weight loss per week is dangerous to a cat and promotes developing a liver disease called hepatic lipidosis. A good goal is 0.5-1% weekly. Your veterinarian can design a weight loss plan. Several therapeutic diets are designed for this use.
Your veterinarian is your best source of information for what to feed your diabetic cat. Obviously, there are individual concerns, concurrent illness that may require diabetic modifications, and logistics issues to consider. You can also see a professional veterinary nutritionist to devise a home made diet. The biggest point is that diet strategy is an important part of diabetic regulation.