Insulin Information & Scales

Specific Insulin Information, Dosing Scales & Dosing Criteria

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.

Insulin is categorized by its duration:

Long acting insulin (in alphabetical order)
– Hypurin Bovine Protamine Zinc – No longer being manufactured, information is included for any that still have some vials.
– 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

Fast acting insulin: Note usually used only in very specific situations (DKA, Acromegaly…). Do NOT try to use a fast acting insulin unless under the advice of your vet.
– NovoRapid (Europe) or Novolog (US)

Note about insulin containing protamine

Protamine is a protein used to add duration to insulins. It is used in all Protamine Zinc or PZI insulins (Hypurin bovine PZI, ProZinc, US/Canadian Bovine PZI) as well as in NPH/Humulin N/Humulin I.

The protamine sulfate used is a protein that is salmon based: even 100% bovine insulins use the salmon suspension for the protamine.

While very rare, cats with allergies to fish, especially salmon, may experience problems with these insulins. If your cat has been tested for and shown allergies to fish, use of another insulin would be advisable.

For cats that are having problems regulating on insulins that do contain protamine, the possibility of a salmon/fish allergy should be taken into account as one of the factors that may be contributing to the situation.

General information

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.

Syringes

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.

Drawing insulin

Drawing insulin depends on the insulin you are using:

Hypurin, Caninsulin/Vetsulin, US PZIs, ProZinc and NPH – insulins in 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) 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 such as Caninsulin/Vetsulin pens
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.

Where to inject insulin on your cat

While many vets will show you to dose in the scruff of the neck, that is not a good place to dose insulin: insulation absorbtion is poor there.

You should inject up and down the body, at least a few inches down from the spine. Do move around and inject in different places to avoid scar tissue from building up.

Here are the good places to dose:

Starting TR

You should start TR at a time when you are able to monitor your cat’s BG frequently over the first few days (for example, starting a Friday evening or Saturday morning if you work during the week). The testing over the first few days will help establish how your cat is assimilating its insulin: when it starts working (onset), when it is strongest and the BG lowest (nadir) and when it starts wearing off.igh

Note: If your cat is on high carb food and needs to follow the full 24-hour Detox without insulin, it is best to start the Detox around 24-hrs before you start TR (dosing): for example, detox as of Thursday evening if you will start TR on Friday evening. Not much “happens” during detox – it is good to test a few times, and in particular around 20-22 hrs after the last shot of insulin. You do not need to be present during the entire Detox period.

More testing and curves are also needed as dosing adjustments take place (whether increases or decreases)

The starting scales noted in this sticky are just that: starting scales. Depending on your cat’s results, they will be adjusted as needed – whether that means increasing or decreasing. In general, adjustments take place after three runs (3 doses of insulin + tests) in order to bring your cat down into better or normal numbers as quickly as possible.

It is important that your cat fall into a range of at least below 250/13.8 as soon as possible. This range is “renal threshold”. Below renal threshold, the chance of ketones, which can lead to a life-threatening Diabetic KetoAcidosis (DKA) are reduced/minimized. ( Please see the Stickies in the Knowledge Centre for more information on Ketones and DKA).

The goal though is to bring your cat down to normal range numbers of 45-130/2.5-7.2, ideally with a nadir in the range of 45-70/2.5-3.9 as quickly as possible.

Switching Insulins

If you are switching insulins, you need to let a minimum amount of time pass in order to let the “old” insulin run out before you start the new insulin. The amount of time depends on the duration of the old insulin.

Hypurin Bovine PZI, Lantus, Levemir: 18-24 hours
US/Canadian Bovine PZI, ProZinc, Caninsulin, NPH: 10-12 hours

The exact timing and when to restart will be based on your cat’s BGs. Experienced members will help you.

Specific Insulin information, Starting Scales & Dosing Criteria

Below you will find specific information about the different insulins, classed by duration.

Long Lasting insulins: Hypurin Bovine PZI, Lantus, Levemir

Hypurin Bovine PZI

Sadly, as of around September 2019, Hypurin Bovine PZI is not longer available due to the impossibility to obtain the raw materials necessary to manufacture bovine based insulins today. The information below is for anyone who may have some vials in reserve. Hypurin Bovine PZI was an excellent insulin for cats, so it is truly a shame that it can no longer be manufactured.

General Information:

Hypurin Bovine PZI is the only manufactured bovine insulin that exists in the world today. It is manufactured by CP Pharma/Wockhardt in the UK.

The fact that it is manufactured, rather than compounded (see US/Canadian Bovine PZI insulins) means that it is very stable.

Hypurin Bovine PZI is the longest lasting of any insulin used on cats (only one other longer lasting insulin exists at all: Insulin degludec (trade name Tresiba). On humans it can last up to 36 hours. On cats that have used it with TR it has shown to last 24-30 hours in certain circumstances. It works very differently from US/Canadian PZI insulin, and cannot at all be considered in the same category as them.

It is a bovine based insulin: while unfortunately there is no insulin that is identical to a cat’s insulin, bovine based insulin is the closest to that of a cat – it is only one amino acid away from that of a cat’s.

Hypurin can be imported into Europe and Canada (a 3-month supply for personal use) via MastersGlobal . While theoretically it may be possible to import to the US, health regulations make it pretty much impossible to do so. (Please see the Canadian Information sticky for details including customs documentation information).

Hypurin is a U100 insulin that needs to be dosed with U100 syringes only.

It is a very interesting insulin given its exceptional duration . At the same time, the duration makes it a little more complicated than other insulins to find the right scale and dosing times – the overlap between doses – the amount of insulin left from the last dose vs. when you now dose – is very significant and need to be taken into consideration.

Duration and the way that Hypurin works can vary and there can be quite large ranges of time for onset, nadir and when it starts leaving the system.

In humans, onset is around +4-+6 (4-6 hours after dosing). Nadir, when Hypurin is strongest and the BG lowest, is anywhere from +10-+20 and it can last as long as 36 hours.

Some cats on Hypurin have shown similar ranges of timing despite the fact that cats usually assimilate insulin much more quickly than humans. With others, nadir has been earlier, and duration also reduced. Testing will show you how your cat is processing Hypurin and will let you make the necessary adjustments to scale and timing of dosing.

Hypurin is very sensitive to small adjustments in dose: adjustments are often usually made by 0.25u or even a fat (0.125u) increments. If your cat is staying in high numbers at the start in particular, or there are ketones present, a 0.50u increase may be suggested, if rarely. Senior Members will help you decide what is best for your cat.

When dosing Hypurin, you should try and hold the syringe in after injecting for a count of 10.

Starting Scale for Hypurin Bovine PZI (After 24-hour Detox):

The recommended starting scale for Hypurin is the following:

Imperial BG……….Metric BG………..Dose of insulin
151 – 185 …………..8.3 – 10.2 ……………..0.25u
186 – 250 ………..10.3 – 13.8……………….0.50u
251 – 350…………13.8 – 19.4……………….0.75u
351 +……………….19.5+……………………..1.00u

Dosing Criteria for Hypurin Bovine PZI:

The dosing criteria to be able to give insulin for Hypurin (all criteria need to be in place) :

• A minimum of 10 hours since the last dose of insulin (depending on your cat’s situation, it is possible that dosing as of +8 will be suggested to start)
• A BG of a minimum of 150/8.3
• A BG that is rising if it is between 150/8.3 and around 225/12.5: if the BG is higher than this it is more important that the cat gets the insulin it needs to bring its BGs down to normal numbers and to maintain overlap

Lantus (Glargine)

General Information

Lantus/Glargine is a U100 human insulin that is therefore dosed with U100 syringes. Glargine is the actual name of the insulin; it is sold under the brand name Lantus.

Lantus is available in 10ml vials or 3ml cartridges or pens. Cartridges are not available in the US. If you have Lantus pens you still need U100 syringes (3/10cc-0.3ml U100 syringes with half unit markings). The pen itself only doses 1u increments. You will need to draw the amount of insulin you need to dose from the cartridge that is in the pen. The top of the cartridge (the rubber stopper) is visible when you take the cap of the pen off. That is where you need to insert the syringe to draw insulin.

If you live in a country where cartridges are available that is recommended. The cartridges cost more… but there is less chance of insulin losing potency vs. the vial as there is less insulin contained in a cartridge, so it will be used more quickly. With the small doses we do use with our cats (vs much higher human doses) we do not go through a vial as quickly as people do. There is therefore much less waste with the cartridges (or pens) vs. the vial.

Lantus is available at any pharmacy or chemists and will probably be less expensive there than if you buy via your vet. If you are in North America, purchasing at Wal-Mart or Costco is probably the cheapest option.

The insulin in the vial or cartridge should be clear. If you see crystals developing, you should discard the vial or cartridge and start with a new one.

Lantus is a long lasting insulin: Onset (when the insulin starts working) is usually around +3-+4. Nadir (when it is strongest and the BG lowest) tends to be around +6-+8 for most cats. It starts wearing off around +8-+10.

Ideally when starting TR at least, +10 dosing works best with Lantus: that timing makes the best use of overlap between the two doses of insulin. A +10 schedule is though very difficult to keep up for most people with professional or other obligations. +12 dosing is possible; it may take a little more time for your cat to become regulated. If you are unable to dose +10 on a regular basis, doing so over weekends/days off and using a +12 base during the week/when you are working is also a strategy that some members have used successfully.

Each insulin has its own challenge… the biggest challenge with Lantus is the way it works. When you inject Lantus it creates a depot under the skin. Insulin is then released over time from there.

Because of the strong depot characteristics of Lantus, it takes 3, or for some cats even 4, doses before you see the full effect of any changes to what you are doing or what has happened (scale adjustments, a longer duration between shots, etc). You do not see “instant” results with lantus.. patience is required!

Lantus is a powerful insulin, and small adjustments may make a big difference. Dosing adjustments are therefore usually made by small increments (0.25u, 0.125u – also known as a fat). Depending on your cat’s results, a larger increase may be suggested. Senior Members will help you with what is best for your cat.

When you dose Lantus, after pushing the plunger down, you should leave the needle in place and slowly count to ten before removing it. When you have removed the syringe, gently apply some pressure to the spot for a few seconds. You should NOT rub the area as that will damage the Lantus molecues.

Starting Scale for Lantus (After 24-hour Detox):

Imperial BG……….Metric BG………..Dose of insulin
150 – 250…………..8.3 – 13.9……………….0.25u
251 – 400………….14.0 – 22.0………………0.50u
400 +………………..22.2 +……………………0.75u

Dosing Criteria for Lantus:

The dosing criteria to be able to give insulin for Lantus (all criteria need to be in place) :
• A minimum of 10 hours since the last dose of insulin
• A BG of a minimum of 150/8.3
• A BG that is rising if it is between 150/8.3 and around 225/12.5: if the BG is higher than this it is more important that the cat gets the insulin it needs to bring its BGs down to normal numbers and to maintain overlap

Levemir (Detemir)

General Information

Levemir arrived in the US quite a bit later than in other countries, and tends to still be less well known there. Detemir is the actual name of the insulin; Levemir is the brand name.

Levemir is available in a vial in some countries. It is much more commonly sold in the form of a pen. You will need to buy and use 3/10cc-0.3ml syringes with half unit markings as the pen only doses in 1u increments. You simply insert the needle into the rubber stopper of the cartridge in the pen, which is visible when you remove the cap.

Levemir is a synthetic U100 human insulin. Rather than creating a depot under the skin like Lantus, it attaches to the albumin in the blood, and then slowly detaches from there and starts to work.

It is pH neutral (vs. Lantus which has a low pH) and is very well tolerated by cats who overall do very well on it. Cats which may have had problems becoming regulated on other insulins have in general been much better regulated on Levemir.

Levemir is a gentle insulin with a curve that is much flatter than most other insulins.

Like Lantus, onset is around 3-4 hours after the shot and nadir tends to be around +6-+8. Its duration is a little longer than that of Lantus for most cats and it will move out to +12 dosing quite quickly.

Starting Scale for Levemir (After 24-hour Detox):

Dosing Criteria for Levemir:

The dosing criteria to be able to give insulin for Levemir (all criteria need to be in place) :
• A minimum of 10 hours since the last dose of insulin.
• A BG of a minimum of 150/8.3
• A BG that is rising if it is between 150/8.3 and around 225/12.5: if the BG is higher than this it is more important that the cat gets the insulin it needs to bring its BGs down to normal numbers and to maintain overlap

Intermediate Lasting insulins: Caninsulin/Vetsulin, NPH, ProZinc, US/Canadian Bovine PZI

Caninsulin/Vetsulin

General Information:

Caninsulin, known as Vetsulin in the US, is a porcine based veterinary insulin used on both cats and dogs. It is identical to dogs’ insulin but is three amino acids away from a cat’s insulin.

Vetsulin was removed from the US market due to production quality issues for quite some time, but has now been available again since early 2014. The formula was changed to what seems to be that used for Caninsulin in the UK and Europe, and cats have been doing better on it than they did with the old formula.

In Europe, Caninsulin is often the first insulin used as it is the only vet insulin available. In some countries, vets “have” to prescribe it as the first insulin – only if the cat is not responding well to it can they prescribe another.

Traditionally, Caninsulin has been known for being a very “harsh” insulin that would drop cats very quickly and then leave the system very quickly, resulting in a roller coaster of low and high numbers. The new Vetsulin formula and that used in Europe though seems to result in smoother curves. A number of cats have done well on it.

Caninsulin/Vetsulin is a U40 insulin. It is available in vials (prescribed with U40 syringes) or in pens that dose in 0.50u increments. Using 3/10cc-0.3ml U100 syringes with half unit markings is possible with both and is strongly recommended as it will allow you to dose smaller increments than the pen allows, and smaller units more accurately with the vials. It is necessary to do a conversion to dose U40 insulin with U100 syringes. Please see the Converting U40 insulin to U100 syringes sticky in the Knowledge Centre for information on the conversion, and post in Introductions & Questions for help.

Onset, when the insulin starts working, is usually around +1-+2 for Caninsulin/Vetsulin (1-2 hours after the shot). Nadir, when it is strongest and the BGs lowest, is around +4-+6. It has usually starts leaving the system by around +8.

+8 dosing is recommended for Caninsulin/Vetsulin.

Starting Scale for Caninsulin/Vetsulin (After 24-hour Detox) using U40 syringes:

Imperial BG……….Metric BG………..Dose of insulin
151-170………….……..8.3-9.4……………….0.25u
171-185……………….9.5-10.2……………….0.50u
186-200……………..10.3-11.1……………….0.75u
201-220……………..11.2-12.2……………….1.00u
221-250……………..12.3-13.8……………….1.25u
251-290……………..13.9-16.1……………….1.50u
291-350……………..16.2-19.4……………….1.75u
351-410……………..19.5-22.7……………….2.00u
411-450……………..22.8-25.0……………….2.25u
451-500……………..25.1-27.8……………….2.50u

Dosing Criteria for Caninsulin/Vetsulin:

The dosing criteria to be able to give insulin for Caninsulin/Vetsulin (all criteria need to be in place) :
• A minimum of 8 hours since the last dose of insulin
• A BG of a minimum of 150/8.3
• A BG that is rising if it is between 150/8.3 and around 225/12.5: if the BG is higher than this it is more important that the cat gets the insulin it needs to bring its BGs down to normal numbers and to maintain overlap

NPH (Humulin N, Humulin I)

General Information

NPH (Neutral Protamine Hagedorn) is a U100 human recombinant insulin. It is also called Humulin N and Novlin N in North America and Humulin I or Isophane outside of North America.

Commonly used on dogs, NPH can provide relatively unpredictable results with cats.

There should be no particles or clumps in the vial – if they do happen, turn the vial over a few times to see if they disappear. If they do not, you should discard the vial.

NPH can be a “rough” insulin for some cats, dropping the BG very quickly and also leaving the system quickly. Some cats though have done well on it – achieving a diet controlled remission.

Onset, when the insulin starts working, can be as early as +1-+2. Nadir is often between +3-+4 and it can leave the system as early as +6. Because of its quick “in and out” action on some cats, doing a curve consisting of hourly tests (rather than the usual every 2 hours) can give some very useful information concerning how your cat is assimilating it. It is an insulin that does best dosed at +6 (every 6 hours) as long as all criteria are in place.

NPH is not the best choice for most cats because of its very short duration and the sharp drops/quick spikes it can provoke in BGs. Again though, some cats have done well on it.

Starting Scale for NPH (After 24-hour Detox):

Dosing Criteria for NPH:

The dosing criteria to be able to give insulin for NPH (all criteria need to be in place) :
• A minimum of 6 hours since the last dose of insulin
• A BG of a minimum of 150/8.3
• A BG that is rising if it is between 150/8.3 and around 225/12.5: if the BG is higher than this it is more important that the cat gets the insulin it needs to bring its BGs down to normal numbers and to maintain overlap

ProZinc

General Information

ProZinc (protamine zinc recombinant human insulin) is the only FDA approved insulin for use on cats. It is available in the US, and as of 2015 in Canada also. Now, in 2016, it is starting to arrive in Europe.

It is a manufactured insulin, so is very stable. It will often be prescribed by vets in the US as it is the only officially approved insulin for cats.

ProZinc is a U40 insulin, so is dosed using U40 syringes. Using 3/10cc-0.3ml U100 syringes with half unit markings is possible and will allow you to dose more accurately. It is necessary to do a conversion to dose U40 insulin with U100 syringes. Please see the Converting U40 insulin to U100 Syringes sticky in the Knowledge Centre for information on the conversion, and post in Introductions & Questions for help.

Onset with ProZinc (when the insulin starts working) is around +2-+3 (2-3 hours after the dose of insulin). Nadir (when its action is strongest and the BG lowest) is around +4-+6 for most cats. In general, it starts wearing off by +8.

+8 dosing is recommended with ProZinc.

Starting Scale for ProZinc (After 24-hour Detox) using U40 syringes:

Dosing Critera for ProZinc

The dosing criteria to be able to give insulin for ProZinc (all criteria need to be in place) :
• A minimum of 8 hours since the last dose of insulin
• A BG of a minimum of 150/8.3
• A BG that is rising if it is between 150/8.3 and around 225/12.5: if the BG is higher than this it is more important that the cat gets the insulin it needs to bring its BGs down to normal numbers and to maintain overlap

US/Canadian Bovine Protamine Zinc (PZI) Insulin

General Information

Bovine PZI is the closest to a cat’s own insulin, being only 1 amino acid away.

Unfortunately no US/Canadian Bovine PZI insulins are manufactured today: all are compounded. (It is possible to important the manufactured Hypurin bovine PZI into Canada: please see the information on Hypurin in the long duration insulins above, or in the Canadian sticky, for more information).

In the US sources include BCP or Stokes. In Canada Summit compounds Bovine PZI.

BCP offers a free 5ml vial of U100 with a first order from them that is sent to your vet. Most vets will give this free vial to you. The coupon for the free vial may be found on their site: click on the link above.

As the insulin is compounded, rather than being manufactured, there can be differences from one batch to the other, making it a less stable PZI insulin choice than ProZinc in the US. The differences in batches may be the reason why some cats may have trouble becoming regulated on compounded bovine PZIs.

Compounded Bovine PZI insulin is available in both U40 and U100 strengths. The U100 strength tends to have a slightly later onset and nadir, and a longer duration than the U40 strength. U100 is “pure” insulin. U40 insulin is diluted and the hexamers that make up the insulin are already pushed apart by the dilution, so fall apart and enter the system more quickly than the more tightly bound U100 hexamers.

The U100 strength needs to be dosed with U100 syringes. The U40 strength may be dosed with the 3/10cc-0.3ml U100 syringes with half unit markings also, providing greater accuracy with dosing. It is necessary to do a conversion to dose U40 insulin with U100 syringes. Please see the Converting U40 insulin to U100 syringes sticky in the Knowledge Centre for information on the conversion, and post in Introductions & Questions for help.

While timing may again be slightly later with the U100 strength, in general for most cats compounded Bovine PZI starts working at onset at around +2-+3 (2-3 hours after the dose of insulin). It is strongest and the BGs lowest at nadir at around +4-+6. It then starts wearing off by around +8.

+6 dosing is recommended to start, if your schedule allows that.

Starting Scale for US/Canadian Bovine PZI (After 24-hour Detox) using U100 syringes with the U100 strength/U40 syringes with the U40 strength:

Dosing Criteria for US/Canadian Bovine PZI:

The dosing criteria to be able to give insulin for US/Candian Bovine PZI (all criteria need to be in place) :
• A minimum of 6 hours since the last dose of insulin
• A BG of a minimum of 150/8.3
• A BG that is rising if it is between 150/8.3 and around 225/12.5: if the BG is higher than this it is more important that the cat gets the insulin it needs to bring its BGs down to normal numbers and to maintain overlap

Fast Acting insulins: NovoRapid (Europe & Canada) / Novolog (US)

NovoRapid (Europe & Canada) / Novolog (US)

General Information

Fast acting insulin is used above all when a cat has developed high level ketones and/or is suffering from a DKA (Diabetic Ketoacidosis). It may also be used in the case of a cat that is very difficult to regulate on one of the longer duration insulins, for example for an acromegalic cat.

Fast acting insulin drives the BGs down very quickly, usually starting to work by +1 (1 hour after the shot of insulin). It usually has completely left the system by +3-+4. As for the other insulin types, a scale approach is used with it.

It may be dosed in conjunction with a long lasting insulin (Lantus and Levemir in particular) or dosed alone.
Use is on a cat by cat basis, depending on the specific situation; overall guidelines are therefore not provided.

Please post in Introductions & Questions for guidance about their use and always confer with your vet as to whether using them is appropriate for your cat and its specific situation.

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Last update: February 2021