Tanya's Comprehensive Guide to Feline Chronic Kidney Disease

It is not uncommon for a CKD cat to also have or develop diabetes.
The dietary needs of a diabetic cat may seem incompatible with the needs of a CKD cat but the diabetes must take precedence.

What is Diabetes? Back to Page Index

Diabetes mellitus is a disease in which not enough insulin is produced by the pancreas, or the cat’s body cells do not properly process insulin which the pancreas has produced. Insulin is needed in order to enable the body to process food and to produce energy from it. If this mechanism is faulty, the cat develops hyperglycaemia (high blood sugar levels), which eventually leads to high sugar levels in the urine (glucosuria).

There are two forms of diabetes mellitus, uncomplicated and diabetes with ketoacidosis. Cats with the former may only have mild symptoms, at least in the early stages, but cats with ketoacidosis are usually very ill, and may die if not treated promptly.

Obesity in cats, as in humans, is a strong predisposing factor for diabetes. Cats who are on corticosteroids may also develop diabetes, but this may disappear once the steroids are stopped (which should always be done gradually). Going into remission is relatively common in cats with well controlled diabetes, even if they are not on steroids.

Predictors of clinical remission in cats with diabetes mellitus (2010) Zini E, Hafner M, Franchini M, Ackermann M, Lutz TA & Reusch CE Journal of Veterinary Internal Medicine 24(6) pp 1313-21 found that 50% of cats in the study went into remission and that this was more common in older cats.

Feline diabetes mellitus: from diagnosis to therapy (2009) is a helpful article by Dr DL Zoran.

Feline diabetes - five principles breed success (2009) is an article by Dr Gary Norsworthy in the October 2009 edition of Veterinary Practice News.

Symptoms Back to Page Index

The increase in sugar in the urine causes polyuria (increased urination) and polydipsia (increased drinking). Diabetic cats also tend to lose weight, so to some extent the symptoms of diabetes may resemble those of CKD, although there is one noticeable difference, namely that diabetic cats tend not to lose their appetites – they lose weight despite continuing to eat, and may in fact eat more (this can also be a symptom of hyperthyroidism).

More advanced diabetes may also cause lack of appetite, poor coat quality, vomiting and dehydration and occasionally breathing problems. Bladder infections are also relatively common because of the sugar in the urine, and inappropriate elimination may occur.

Back leg weakness may be caused by diabetic neuropathy, where the nerves in the legs are damaged by the disease. The Mayo Clinic has information about peripheral neuropathy, including that caused by diabetes.

Diagnosis Back to Page Index

The vet will base the diagnosis on bloodwork, clinical signs, and high levels of sugar in the blood and urine on an ongoing basis. Cats who are stressed by vet visits may sometimes have high blood glucose levels, so this is not necessarily a definite sign of diabetes, it is the ongoing nature of the increased glucose level that is important. For this reason, it is a good idea to check fructosamine, which measures concentrations of glucose molecules historically over a period of approximately 2-3 weeks. Lab Tests Online has an overview of the fructosamine test.

Cats with ketoacidosis may have elevated BUN and creatinine levels, which in this situation may not necessarily be a sign of CKD, particularly if phosphorus and potassium levels are normal. Diabetic cats also often have dilute urine unrelated to CKD, and the resulting dehydration may also cause increased kidney values. Once the diabetes is under control, the BUN and creatinine levels may improve. Initially the bloodwork may also indicate liver damage, which should improve as the diabetes is brought under control.

Treatments Back to Page Index

Insulin
Oral medications
Diet

Cats with ketoacidotic diabetes normally require hospitalisation including IV fluids and insulin therapy, until they are stabilised; thereafter they will be treated as cats with uncomplicated diabetes.

Cats with diabetic neuropathy often benefit from Vitamin B12 in the form of methylcobalamin. Jasper's Page has more information on this treatment.

Controlling any infection that is present, such as a urinary tract infection, may make the diabetes easier to control.

Insulin

Uncomplicated diabetes is usually managed by means of insulin injections. Bovine insulin is most similar genetically to feline insulin, and is readily available in the UK; however, in the USA animal-based insulins are often imported from the UK and may be relatively expensive. The insulin is administered once or twice daily, and cats vary in their response, so the amount and the frequency are determined by checking blood glucose levels. This needs to be done every few hours at first and may be done in hospital initially, but gradually the frequency of checks can be reduced to once or twice a day (see monitoring). If the diabetes is properly controlled, the earlier symptoms should disappear.

Cornell University College of Veterinary Medicine has a video covering all aspects of diabetic cat care, including how to give insulin, monitoring your cat, and recognising and treating hypoglycaemia.

Oral Medication

Sometimes diabetic cats can be treated with an oral medication called glipizide instead of injectable insulin. However, only about 30% of diabetic cats respond to glipizide, and cats taking it must be carefully monitored because the drug can damage the liver. In any event, most cats are far easier to inject than to pill.

Diet

Diabetic cats also require their diet to be monitored. Your vet can advise you on frequency of feeding, but usually cats receiving insulin twice a day are fed half their daily food ration each time; free feeding is not normally appropriate for diabetic cats. Cats receiving glipizide are normally fed several small meals a day.

High fibre, high complex carbohydrate diets (such as Hill’s w/d diet) are sometimes recommended for diabetic cats because it used to be believed that they might help to control blood glucose levels. However, cats have a low natural requirement for carbohydrates, and more recent research in fact indicates that higher protein, higher fat and lower carbohydrate diets may be more suitable for diabetic cats. Suitable foods for this approach include Purina DM (Diabetes Management) veterinary formula (not currently available in UK), and kitten foods, which are usually high in protein and fat. Hill's have a similar food called Hill's m/d (click on Prescription Diet, then on Cat, then on m/d), which also has a relatively low phosphorus level of 0.7% on a dry matter analysis basis. It is important to try to moderate phosphorus intake for cats with both CKD and diabetes, and if necessary, phosphorus binders will need to be used.

There is some debate as to whether dry food is appropriate for diabetic cats. Indoor confinement and physical inactivity rather than the proportion of dry food are risk factors in the development of feline type 2 diabetes mellitus (2009) Singerland LI, Fazilova VV, Plantinga EA, Kooistra HS & Beynen AC Veterinary Journal 179(2) pp247-253 found no evidence that dry food diets in themselves cause diabetes in cats. However, some diabetic cats are so sensitive to carbohydrate that they need less insulin, or in a few cases stop needing it all together, when switched to a low carbohydrate diet. Generally speaking, canned foods are much lower in carbohydrate than dry foods, so canned foods low in cereals and added sugars may be helpful in such cases, but dry foods may be less unsuitable because they tend to have a high carbohydrate content.

Diet changes should be made gradually if a cat is already taking insulin, and blood glucose levels should be carefully monitored, because sometimes there is a dramatic drop in blood glucose in response to reduced carbohydrate, with a possible risk of an overdose of insulin (see hypoglycaemia).

Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus (2005) Bennett N, Greco DS, Peterson ME, Kirk C, Mathes M, Fettman MJ. Journal of Feline Medicine and Surgery Nov 3 found that the diabetic cats in this study who were fed the low carbohydrate-low fibre diet were significantly more likely to cease to need insulin than the cats fed the moderate carbohydrate-high fibre diet.

Diet in the prevention of diabetes and obesity in companion animals (2003) Rand JS, Farrow HA, Fleeman LM & Appleton DJ Proceedings of the Nutrition Society of Australia discusses how dietary changes may help with diabetes control.

Monitoring Back to Page Index

Home blood glucose testing
Hypoglycaemia

You will probably need to check urine ketone levels using dipsticks (Ketostix, available from pharmacies). Even a trace of ketones is a cause for concern and warrants an immediate vet visit. Urine glucose is only really useful for initial diagnosis – healthy cats do not have glucose in their urine – because it is too imprecise a measure to make proper decisions about insulin dosage.

Home Blood Glucose Testing

You will also need to monitor your cat's blood sugar levels, and may wish to do this at home using a glucometer (available from pharmacies for use by human diabetics) – home monitoring is much cheaper for you and less stressful for your cat. The blood can normally be taken from the ear using a sterile lancet, and only a tiny amount is required, though many UK vets are unfamiliar with this approach. Generally speaking, a cat is considered regulated if his/her blood glucose consistently remains in the 5-15 mmols/l (US: 100-300 mg/dl) range.

Sometimes cats are started on too high a dose of insulin, which leads to a sudden drop in blood sugar levels, and the body reacts to this by releasing glucagons which raise blood sugar levels again. It thus appears, based on spot checks at the vet's, that the cat requires even more insulin, when in fact the opposite is the case. This is known as the Somogyi Effect. Home blood glucose monitoring gives more accurate results and can help you to avoid such problems.

Veterinary Partner has step by step instructions for home blood glucose testing with a slide show guide.

Sugar Cat Harry's Website has detailed information on home blood glucose testing.

Feline Diabetes has information on the Somogyi Effect.

Hypoglycaemia

As a general rule, too much insulin is far more dangerous for a diabetic cat than too little, and may cause low blood sugar (hypoglycaemia). Symptoms include weakness, lack of co-ordination, convulsions and coma. The cat should be offered food immediately if still able to eat, or you may need to rub corn syrup or powdered glucose on the gums (in UK you can also buy a human OTC diabetic product called Hypo-Stop); otherwise you should contact your vet urgently. You will need to discuss your treatment programme with your vet in any event following an incident of hypoglycaemia.

Gorbzilla has information on hypoglycaemia.

Diabetes and CKD Back to Page Index

If you are dealing with both diabetes and CKD, it is more important that the diabetes should be regulated, and in fact once this is achieved, you may find the CKD improves too. Please also see diagnosis above.

People dealing with both diabetes and CKD are sometimes anxious because it appears that the protein requirements of the two conditions are incompatible, but in fact low protein is not necessarily essential in the treatment of CKD, see Nutritional Requirements and diabetes diet for more information.

A dehydrated cat may respond less well to insulin, and many owners have found that once sub-Qs are begun, the insulin seems to work more effectively, sometimes with longer duration than was previously the case.

Anecdotal evidence suggests that diabetic cats with CKD do less well on benazepril (Fortekor) than cats with CKD only.

Links Back to Page Index

General Overviews

Keys to management of diabetes in cats (2011) is a presentation by Dr S Little to the 36th World Small Animal Veterinary Association World Congress which compares the various brands of insulin available and advises on how to adjust insulin dosage.

Cornell University College of Veterinary Medicine has a good general overview.

Washington State University also provides a good overview.

Feline Diabetes Message Board FAQs provide detailed answers to frequently asked questions.

Gorbzilla has lots of practical information, including information in German.

Support

Feline Diabetes Message Board has a very busy message board and a helpful website too.

Pet Diabetes Group is a group which covers cats and other species; it also has an associated website.

Feline Diabetes Group is a group for people dealing with diabetes in cats.

Feline CRF-FD Group is a newer group for people dealing with both CKD and diabetes.

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This page last updated: 16 October 2011

Links on this page last checked: 16 October 2011