Diabetic cat -insulin-2


While Tight Regulation (TR) was originally established around the use of US Bovine PZI insulin, the protocol has been adapted and successfully used with all insulin types today.

Each insulin works slightly differently and different insulin will have different durations. Some do tend to be more adapted to cats than others. The duration may mean that some work better for you because of the times you are able to dose and test around work or other obligations.

TR has helped cats no matter what insulin they are on.


The Different Insulins

Insulin is categorised by its duration:

Long acting insulin (in alphabetical order)
– Lantus (Glargine)
– Levemir (Detemir)

Intermediate acting insulin :
– Caninsulin (known as Vetsulin in the US)
– NPH (also known as Humulin N in North America or Humulin I in Europe)
– ProZinc
– US/Canadian Bovine PZI (Protamine Zinc Insulin)

Long acting insulin


Lantus (Glargine)

Lantus is available around the world.  It usually lasts around 10-12 hours on cats.

Lantus creates a depot under the skin.  The insulin molecules then break up and enter the system.

Because of the way it works, it takes three or even four doses with the same scale to see the full effect of any changes.  Lantus therefore does require some patience.

Levemir (Detemir)

While Levemir has been available in some markets for a long time, it is a little newer on the US market and not as well known there.

Levemir is a gentle insulin that cats seem to tolerate very well – and do very well on.

Its duration is slightly longer than that of Lantus for most cats.

Intermediate acting insulin

Caninsulin (Vetsulin in the US)  is a veterinary insulin – the only one available outside of North America. 

For that reason it is often the first insulin prescribed.  In many European countries, Caninsulin needs to be tried first, and only if the cat is not responding well, will another insulin be tried.

Caninsulin can make the blood glucose levels of some cats drop quite quickly – and consequently bounce quite high after the drop.

It rarely lasts for more than 8 hours until the cat has started healing.


NPH can be quite a rough insulin for many cats, and can cause very sharp drops and very high peaks.  It is quite a harsh insulin for cats, and is not recommended.  Cats using it have, however, gone into diet-controlled remissions using the Tight Regulation Protocol. 

It usually lasts around 6 hours in cats.


ProZinc is the second vet insulin.  Orginally only available in the US, it is all now on sale in both Canada and Europe. 

It is a manufactured U40 protamine zinc insulin and is specifically for use on cats (not dogs).

It lasts 6-8 hours on cats – usually moving to 8 hours quite quickly.

US/Canadian Bovine PZI insulins

Compounded Bovine PZI insulin is available in the US & Canada.

To note:  these insulins are completely different from Hypurin Bovine PZI.

As they are compounded, there may be some problems with stability between different batches.

Duration is usually around 6 hours, with the duration moving out a little bit over time.

Compounded bovine PZIs are available in U40 and U100 form:  the U100 may have a slightly longer duration for some cats.


General information on Insulin Storage and Handling

Storing your insulin

You should store your insulin in the fridge (this holds true even for Lantus or Levemir pens with instructions to keep at room temperature). Keeping your insulin refrigerated will prolong its shelf life. It should be stored on a shelf, in a quiet place where it will not be jostled. It should be stored in a sturdy container, and should not be touching the refrigerator walls. Do not store it in the door, which is frequently opened and closed.


You should always use a new syringe each time that you draw insulin. The insulin is sterile, reusing syringes can contaminate the insulin. Aside from bacteria entering the solution, the syringe also picks up rubber from the rubber stopper on the insulin vial or cartridge.

Reusing syringes also results in more painful injections for your cat: the needle is blunted after one injection.

It is recommended that you use 3/10cc-0.3ml U100 syringes with half unit markings, whether you are using a U100 or a U40 insulin.  A conversion is needed to dose U40 insulin with U100 syringes. You will find information on the DCI Forum on the conversion, which is simple to do.

 Drawing insulin

Drawing insulin depends on the insulin you are using:

Caninsulin/Vetsulin, US PZIs, ProZinc and NPH
1) Move the plunger up and down several times in the syringe – this will make it move more smoothly and help you draw the dose more easily
2) Pull the plunger to slightly over the dose of insulin that you want to give
3) Turn the vial over gently several times to make sure that the insulin is well mixed
4) Turn the vial upright, put the syringe needle in and gently push the air in the syringe into the vial
5) Turn it upside down and draw a little more than the dose of insulin into the syringe, then push the excess gently back into the vial with the syringe still in place to arrive at the correct dose

For these insulins, “injecting” air into the vial will help reduce problems of air bubbles in the insulin you draw.

Lantus, Levemir and any insulins in a cartridge rather than a vial
1) Move the plunger up and down several times in the syringe – this will make it move more smoothly and help you draw the dose more easily
2) Push the plunger down firmly all the way
3) Insert the syringe into the vial or cartridge with the plunger pushed down
4) Draw a little bit more than the amount of insulin that you plan to dose
5) Remove the syringe from the vial/cartridge and carefully squirt out the excess to get to your dose onto a paper towel

When using cartridges it is important NOT to inject any air into them – doing so will upset the vacuum that make the plunger inside the cartridge move down. In the case of Lantus in particular, injecting air into the vial if you are using a vial, can lead to it losing potency much more quickly

Air Bubbles

Air bubbles may form in the syringe when you draw. If this happens, make sure that you have drawn more than the dose you are giving into the syringe. Turn it needle up and flick it (just like you have seen on TV or in films!) till the bubbles move to the needle end of the syringe.

Then “squirt” out the bubbles and push out any excess insulin to get to the correct dose.

Air bubbles can also occur with cartridges (whether inside a pen or not). Again, making sure that the syringe plunger is very firmly pushed down when you insert the needle into the cartridge, making sure to not inject any air into the cartridge will help minimize the problem.

Should air bubbles occur, you can try inserting a syringe (plunger as always very firmly pushed down) and “drawing off” the air bubble. Move the tip of the needle inside the cartridge around till it is in the air bubble and draw the air into the syringe.

Please do join us on the Diabetic Cat International Forum for:

  • Full information on the different insulins
  • Information on starting dose scales & dosing criteria
  • How to convert to dose U40 insulin with U100 syringes
  • …. and much more!


Associated Articles:


© Diabetic Cat International 2015 – 2022