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Information for owners of Canine's with Diabetes Mellitus 


Diabetes in animals is very similar to that of humans. 
Therefore this page may contain links that are about humans or other animals. 
Background Information about Insulin

When we eat, our bodies break food down into organic compounds, one of which is glucose. 
The cells of our bodies use glucose as a source of energy for movement, growth, repair, and other functions. But before the cells can use glucose, it must move from the bloodstream into the individual cells. This process requires insulin. 

Insulin is produced by the beta cells in the islets of Langerhans in the pancreas. When glucose enters our blood, the pancreas should automatically produce the right amount of insulin to move glucose into our cells. Canines with type 1 diabetes produce no insulin. Felines with type 2 diabetes do not always produce enough insulin. (Felines can be type 1 or 2 and Canines are always type 1)

Insulin Tips:

- NPH cannot be mixed with any Lente (L or U) insulin, they are chemically incompatible.
- Insulin does not have to be refrigerated if kept at a moderate temp., although it is recommended.
- Do not give cold injections, it could cause discomfort.
- Popular opinion is to dispose of opened insulin after 30 days or 100 sticks.
- To prevent abscesses, infections, and discomfort, only use syringes once.
- Rotation of injection sites is recommended.
- It is best to feed before the injection to make sure the animal eats. (generally 30 min. before)
- Human insulins are shorter acting than animal insulins of the same type.
- Never shake "cloudy" insulins. Roll the bottle between the palms of your hands. 

Duration and Peak Times for the Most Common Insulins

Types of Insulin

There are more than 20 types of insulin products available in four basic forms, each with a different time of onset and duration of action. Plus you have caninsulin, vetsulin and pzi for animals. . The decision as to which insulin to choose is based on a veterinarian's preference and experience, and the canine's blood sugar levels. Among the criteria considered in choosing insulin are: 

how soon it starts working in (onset) 

when it works the hardest (peak time)

how long it lasts in the body (duration)

The following table lists some of the more common insulin preparations available today. Onset, peak, and duration of action are approximate for each insulin product, as there may be variability depending on the animal, the injection site, exercise. The key to regulation is consistency!
Insulin type Insulin Brand Starts in (onset) Peaks in (nadir) Gone by (duration)
Rapid Acting Humalog (lispro)
Eli Lilly
10-20 minutes 1.5-2.5 hours 4-5 hrs
Rapid Acting NovoLog (aspart)
Novo Nordisk
10-20 minutes 1.5-2.5 hours 4-5 hrs
Short Acting Humulin R
Eli Lilly

Novolin R
Novo Nordisk

30-45 minutes 2-4 hours 5-7 hours
Humulin N
Eli Lilly

Novolin N
Novo Nordisk

1-3 hours 4-9 hours 14-20 hours
Intermediate and short-acting mixtures  Humulin 50/50
Humulin 70/30
Humalog Mix 75/25
Humalog Mix 50/50
Eli Lilly

Novolin 70/30
Novolog Mix 70/30
Novo Nordisk

varies according
to mixture
varies according
to mixture
varies according
to mixture
with little peak
Lantus (glargine)
2 hours 6 hours (slight) 18-26 hours
with little peak
Novo Nordisk
1 hour 8-10 hours 18-24 hours

These are only averages, each pet reacts differently to their insulin. 

Another graph showing duration and peak times of some insulins 

Vetsulin is now available in the United States.

For more information visit their website


Caninsulin is made exclusively for animals, but is not yet available in the United States. It is currently available in Europe, Canada, and Australia from your veterinarian. Intervet is currently in the initial stages of getting government approval for its use in the US. This product however is the same kind of insulin as Lilly's Iletin II porcine mixed insulin zinc suspension (lente), only its more dilute for more accurate dosing in small animals (40iu/ml instead of 100iu/ml).

Caninsulin is a lente product, and contains 30% "fast" insulin (semilente) and 70% "slow" insulin (ultralente).

For additional information visit their website.

excerpts by Peter A. Graham


PZI stands for protamine zinc insulin. This is insulin combined with large quantities of a protein called protamine. This protein slows the absorption of insulin from a subcutaneous site. These preparations have a long duration of action, but might sometimes have the problem of poor insulin absorption that also occasionally affects ultralente preps. PZI can be formulated for any species of insulin. In the UK, the veterinary licensed PZI is bovine.
Peter A. Graham
Efficacy of protamine zinc insulin(PZI) for treatment of diabetes mellitus in cats. 
Nelson RW, Lynn RC, Wagner-Mann CC, Michels GM.
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616, USA.
 Link to the article 
OBJECTIVE: To evaluate effects of protamine zinc insulin (PZI) on control of glycemia in cats with newly diagnosed diabetes mellitus or poorly controlled diabetes. 
DESIGN: Clinical trial. 
ANIMALS: 67 diabetic cats. 
PROCEDURE: 34 cats with newly diagnosed diabetes and 33 cats with poorly controlled diabetes were treated with PZI twice daily for 45 days. Control of glycemia was assessed on days 7, 14, 30, and 45 by evaluation of clinical response, change in body weight, serum fructosamine concentration, blood glucose concentration measured 1, 3, 5, 7, and 9 hours after administration of PZI, lowest blood glucose concentration, and mean blood glucose concentration during the 9-hour period after administration. Adjustments in dosage of PZI were made as needed to attain control of glycemia. 
RESULTS: For all cats, a significant increase in mean dosage of PZI and significant decreases in 9-hour mean blood glucose concentration, lowest mean blood glucose concentration, and mean serum fructosamine concentration were detected. For cats with poorly controlled diabetes, 9-hour mean blood glucose concentration and mean serum fructosamine concentration were significantly decreased on day 45, compared with day 0. Ninety percent of owners reported improvement or resolution of clinical signs by day 45.
CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that PZI was effective for control of glycemia in cats with newly diagnosed or poorly controlled diabetes and may be used as an initial treatment or as an alternative treatment in cats that do not respond to treatment with other types of insulin.

Lantus insulin is now being used for cats with some success.

PZI and Lantus (insulin for felines both have about the same action)
Starting Dosage:
* 0.25 units per pound twice a day for BG numbers 360 or greater and 0.10 Units per puund for BGs less than 360.
For a 10 pound cat 2.50 units twice daily for blood glucose greater than 360
For a 15 pound cat 3.75unit twices daily for blood glucose greater than 360
For a 15 pound cat 1.50 units twice daily for blood glucose less than 360
For a 10 pound cat 1.00 unit twice daily for blood glucose less than 360
* PZI and Lantus should be kept in the refrigerator (always look at expiration date)
* Opened vials of PZI have a shelf life of 30-90 days and Lantus 30 days. 
  (home testing will help you best determine effectiveness)
Syringes Recommended:
* U-40 syringes for PZI and U100 syringes for Lantus
* PZI syringes can be purchased on-line without a prescription at http://hocks.com *Lantus need a prescription.

A study on three insulins in cats. glargine is another name for lantus
Marshall RD, Rand JS, Morton JM.
Centre for Companion Animal Health, School of Veterinary Science, 
The University of Queensland, Brisbane, Australia, and The Cat Clinic, 
Mt Gravatt, Brisbane, Australia.
 Link to the article 
The pharmacological effects of glargine, protamine zinc (PZI), and lente insulins were evaluated in nine healthy cats. A 3-way crossover study was performed and plasma concentrations of insulin and glucose were determined for 24 h after a single subcutaneous injection of each insulin at 3-day intervals. Time to onset of action did not differ between insulins. Mean time to first nadir glucose was longer for glargine (14 h) relative to PZI (4 h) and lente (5 h). PZI was biphasic in action with nadirs at 4 and 14 h with the second nadir occurring at a similar time to glargine. Nadir glucose did not differ significantly between insulin types. The duration of action was similar for glargine and PZI and was longer than that for lente insulin. Mean daily glucose after glargine and PZI were also similar and were lower than after lente insulin. Time to reach peak insulin did not differ between insulin types. Time to return to baseline insulin level for PZI was longer than glargine but did not differ significantly from lente. In conclusion, healthy cats injected subcutaneously with glargine, compared to those injected with lente insulin, have a later glucose nadir and longer duration of action. Glargine and PZI had similar durations of action in study cats but a larger study is required to obtain precise comparisons of duration of action.

Use of glargine and lente insulins in cats with diabetes mellitus.
Weaver KE, Rozanski EA, Mahony OM, Chan DL, Freeman LM.
Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536, USA.
 Link to the article 
The goals of this study were to compare the efficacy of once-daily administered Glargine insulin to twice-daily administered Lente insulin in cats with diabetes mellitus and to describe the use of a high-protein, low-carbohydrate diet designed for the management of diabetes mellitus in cats. All cats with naturally occurring diabetes mellitus were eligible for inclusion. Baseline testing included a physical examination, serum biochemistry, urinalysis and urine culture, serum thyroxine concentration, and serum fructosamine concentration. All cats were fed the high-protein, low-carbohydrate diet exclusively. Cats were randomized to receive either 0.5 U/kg Lente insulin q12h or 0.5 U/kg Glargine insulin q24h. Re-evaluations were performed on all cats at weeks 1, 2, 4, 8, and 12, and included an assessment of clinical signs, physical examination, 16-hour blood glucose curve, and serum fructosamine concentrations. Thirteen cats completed the study (Lente, n = 7, Glargine, n = 6). There was significant improvement in serum fructosamine and glucose concentrations in all cats but there was no significant difference between the 2 insulin groups. Four of the 13 cats were in complete remission by the end of the study period (Lente, n = 3; Glargine, n = 1). The results of the study support the use of once-daily insulin Glargine or twice-daily Lente insulin in combination with a high-protein, low-carbohydrate diet for treatment of feline diabetes mellitus.

How do I store my insulin?

Frequently Asked Questions About Insulin
Preparing a single dose of insulin
Preparing a mixed dose of insulin
Injecting Insulin
Insulin Administration & Proper Usage
Insulin by Jennifer Prince, D.V.M.
All About Insulin
Insulin Pens 
Tips On Humalog 
Tips on Lantus 
Human Insulin 70/30 
Human Insulin Regular (R) - RxList Generic Information 
Human Insulin NPH - RxList Generic Information 
Insulin Survey in Dogs 
Questions about Insulin 
Insulin Resistance 

BDô INJECT-EASE® Automatic Injector
Painful Insulin Injections in Pets - Tips - Why you should not reuse needles
Can I Prefill Insulin Syringes
Should I give insulin if my pet is ill?
Diabetes Mellitus | Insulin | Your Care Kit | FAQs | Blood Glucose Chart
Sissy and Dakota | Canine Cuisine | Glossary | Mail Lists | Bookmarks
Ken's Daisys Home Blood Glucose Test Site | Pets with Diabetes
Feline Diabetes | Diabetes Mellitus Pet Diabetes Database
The information on this site is general, and should not be used as a substitute
for advice from your veterinarian. Questions concerning your pet's health 
should be directed to your pet's health care provider. 

This page was updated on June 1, 2006