Diabetes in Pets

When your pet is first diagnosed with diabetes, your goal is to "regulate" the pet's blood glucose, which may take a few weeks. This process is basically the same as in type-1 diabetic humans. The goal is to adjust diet and insulin dose to keep the blood glucose values in a comfortable range for the pet during the whole day, or most of it. Regulated cats or dogs can "slip out" of regulation at any time because the body is not a static system.

Regulation is best done with home blood sugar testing and a species-appropriate diet.

The well-regulated diabetic pet should look and act the same as he/she did before diabetes, or like any other non-diabetic pet[1].


For cats, more and more vets are turning to a Low-carb diet to keep the cat's blood sugar levels as constant as possible and allow regulation with a single slow-acting insulin such as PZI, Levemir or Lantus. In this case, the effect on blood sugar of mealtimes is minimal.

Dogs may in some cases have their mealtimes strictly scheduled and planned to match with injection times. Cats on faster-acting insulins such as Vetsulin, Caninsulin, Humulin N, or Lente may also benefit from scheduled meals. Free-feeding can work if the amount of food is measured and kept consistent[2]. Consult your veterinarian.

For dogs, the most common protocol is feeding and giving insulin injections 12 hours apart, with an Intermediate-acting insulin[3][4]. Meals should be timed so that the maximum effect of the injected insulin occurs after it's been eaten, or post-prandially[5].

Since the insulin regimen for most dogs is of a fixed pattern, having a predictable glycemic response should be achieved each time. This means that each meal should be comprised of roughly the same ingredients and caloric content and fed at the same times each day. If food and insulin time varies from time to time for a period upwards of an hour--food and insulin being given up to an hour earlier or delayed by up to an hour, generally there should not be a problem[6]. Being consistent with food and insulin times makes for the best results[7].

Adding more fiber to a dog's diet can be of help with both overweight and regulation. Insulin resistance can come, at least in part, because a pet or person is too heavy. Fiber helps with weight loss because it allows one to feel "full" without the need to consume more food. Those who have food spikes may find they can be eliminated or made manageable by putting more fiber in their diet[8][9]. Putting the brakes on food spikes means coming closer to regulation. Overall because it helps reduce or eliminate some of these Obstacles to regulation, more fiber can mean less insulin[10].


Note that some veterinarians still use the outdated recommendation of using Humulin N or NPH insulin for cats. This insulin is too fast-acting for most cats (though fine for dogs and humans)[11]. A cat's metabolism seems to go through insulin about twice as fast as a human's, and the often-effective slower-acting Lente and Ultralente (Humulin L and Humulin U) insulins were discontinued (as of 2005), so most successfully regulated cats are now using either the veterinary PZI insulins, or the new full-day analogs glargine (Lantus) and detemir (Levemir).

Long acting insulins (such as Lantus,[12][13] Ultralente, PZI) have a poor success rate among dogs. Most are well-controlled with one of the Intermediate-acting insulins-a Lente, an NPH or even one of the non-analog R/Neutral-isophane/NPH mixed insulins[14] given twice daily, most commonly at 12 hour intervals after meals. It is the rare dog who requires regular injections of short-acting insulin in addition to the NPH or Lente given after meals.


The commonly recommended method is to Start Low-Go Slow[15][16][17][18]:

  1. A vet's initial dose recommendation may be based on blood tests done at the vet's. These tests are often elevated artificially by the stress of being at the vet's. It's best to check with a curve at home with a regular human glucometer. Hometesting blood glucose levels just before each shot and at midpoint is essential -- it will save many expensive trips to the vet, avoid dangerous overdoses, and give you a better handle on your pet's ongoing condition. Urine testing stix are not accurate enough for this[19].
  2. The initial dosage should be very conservative (low) (usually between 0.5 and 1 unit twice a day, every 12 hours) and may or may not affect the pet's symptoms noticeably at first. This is necessary because although high blood sugar can cause ongoing damage and eventually death, low blood sugar can kill in minutes. Dosage must be increased gradually and carefully. The usual recommended method is to increase the dose by 1/2 to 1 unit every 2-4 days, followed by further blood glucose testing. An initial decrease may also be necessary --it is fairly common for the initial recommendation to be a little bit too high, especially if it was estimated by weight. A decrease also would be needed if your pet experiences an episodic or chronic Somogyi rebound.
  3. Your pet is "regulated" when its blood glucose remains within an acceptable range all day, every day. Acceptable levels vary somewhat between cats, dogs, and vets, but is roughly from 5 to 12.5 mmol/L (90 to 250 mg/mL in the USA) for cats, and between 5 and 10 mmol/L (90 to 180 mg/dL)[20] for dogs. (The range is wider for diabetic animals than non-diabetic, because shots cannot replicate the accuracy of a working pancreas.) It's important, though, that the glucose level be in the lower half of that range for as much of the day as possible. If you are not testing blood glucose levels at home, some vets recommend that you stop increasing the dosage when the dog or cat is drinking normally, urinating normally, and eating normally, although organ damage may continue in some cases until glucose is below the renal threshold -- testing urine with keto/glucostix will show when this has been achieved.
  4. If after a few weeks of this procedure, your pet's blood glucose level is still high, continue on to read about obstacles to regulation and curves.

Tighter control[]

in cats[]

Dr. E. Hodgkins, Dr. J. Rand, and lately some others are now advocating[21][22] tighter control of blood glucose level in cats, starting as soon as possible after diagnosis. They believe that tight regulation leads to a fast remission of diabetic symptoms, and reduction of complications if begun quickly enough. The risk of hypoglycemia is balanced against the benefit of quick remission. See Tight regulation for some tested protocols that can achieve this goal in cats.

in dogs[]

All dogs will definitely benefit from tight control of blood glucose level, as it prevents long-term complications of diabetes, such as neuropathy,kidney damage, and blindness[23][24]. Remaining above Renal threshold of 180 mg/dl or 10 mmol/l[25] can cause permanent blindness in dogs as well as other bodily complications.

Further Reading[]


support group for caregivers and diabetic pets http://pets.groups.yahoo.com/group/Oscars_animaldiabetes_support/



  1. Diabetes Mellitus-Petplace.com
  2. Caninsulin-Feeding-Page 7
  3. Long-Term Management of the Diabetic Dog-2000-Fleeman & Rand-Pages 2 & 3
  4. BD Diabetes-Insulin Choices-Dogs
  5. Vetsulin-Timing of Meals
  6. BD Diabetes-Insulin Injections for Dogs
  7. BD Diabetes-Diet & Exercise for Diabetic Dogs
  8. BD Diabetes-Diet & Exercise for Diabetic Dogs
  9. Vetsulin-Page 8-Diet
  10. Increasing Fiber Can Mean Reduced Insulin Needs
  11. Selecting an Insulin for Treatment of Diabetes Mellitus in Dogs & Cats-Nelson-Page 41
  12. Fleeman & Rand-Comparison of Pharmacodynamics & Pharmacokinetics of Glargine (Lantus), Protamine Zinc (PZI) & Pork Lente in Dogs
  13. Selecting an Insulin for Treatment of Diabetes Mellitus in Dogs 7 Cats-Page 41
  14. Long-term Management of the Diabetic Dog-2000-Fleeman & Rand-Page 3
  15. Start Low - Go Slow
  16. Dr. Ian Blumer's Practical Guide to Diabetes
    An MD who advises his human patients to Start Low and Go Slow.
  17. Dr. Blumer's Letter to Newly-Diagnosed Human Diabetics in His Practice
  18. Selecting an Insulin for Treatment of Diabetes Mellitus in Dogs & Cats-OSU Endocrinology Symposium 2006-Nelson-Page 41
    Dr. Nelson relates his preference for the method for both dogs & cats and why.
  19. Vetsulin-Urine Monitoring-Page 15
  20. Beyond Insulin Therapy: Achieving Optimal Control in Diabetic Dogs-Drs. Fleeman & Rand- U. Queensland 2005
  21. Rand and Marshall: Understanding Feline Diabetes Mellitus: Pathogenesis and Management
  22. Dr. Elizabeth Hodgkins: Protocol for feline diabetes treatment
  23. Intervet-Guidelines for Successful Diabetes Management-Page 3
  24. Caninsulin Glossary-Complications
  25. Caninsulin Glossary-Renal Threshold