Converting from U40 syringe to U-100

Discussion in 'Caninsulin / Vetsulin and N / NPH' started by sweetcherrypie, Jul 28, 2010.

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  1. sweetcherrypie

    sweetcherrypie Member

    Jul 18, 2010
    Hello everybody,
    I cannot get the hang of the posts! :? I seem to have messages all over the place including messages that have not been sent!
    I have had lots of good advice from everybody, thank you all so much and have decided to change to Insuvets PZI as a result of all your help.
    Unfortunately my vet would not change my cat over to this new Insulin until I got her stabilsed. I am also going away tomorrow and have a query with regards to using the U-40 Caninsulin with the new U-100 syringes. I have had to purchase these as I run out of U-40 syringes before the changeover to the new PZI Insulin on Saturday week. A couple of you have given me the link to the U40 to U-100 conversion chart and I am a bit confused about the dosage and would hate to overdose my cat.
    If the U-100 is stronger than the U-40 why do you give more Insulin instead of less? Is it because the U-40 syringe is .5ml and the U-100 is 0.3ml?
    Kate and Mary I am now feeding more food and directly after shot and Carbonel seems a lot better with better readings between 6 and 15. Not yet regulated though probably never will be on the Caninsulin. I sent you a message Kate and then foregot to post readings as I struggled to meet work deadlines, sorry. I would appreciate some help with the above though.
    Thanks again
    Carol and Carbonel
  2. Phoebe_TiggyGA_NortonGA

    Phoebe_TiggyGA_NortonGA Well-Known Member

    Dec 29, 2009
    U40 insulin has 40 units of Insulin per 1 cc (= 1 milliliter)

    U100 insulin has 100 units of insulin per 1 cc --- so it is stronger for the same amount of liquid. (or you can think of U40 as DILUTED in comparison)

    You give the SAME amount of INSULIN 1u = 1u regardless of the concentration

    If you hold the syringes close to each other and compare -- 1u of U40 is a lot bigger than 1u of U100 because of the concentration.

    U40 1u = 1 ml/ 40 = 0.025 milliliter

    U100 1u = 1 ml/ 100 = 0.01 milliliter <== the syringes are much smaller

    SO In order to use U100 syringes with U40 insulin, you need to multiply by 2.5

    To get 1 unit of U40, you need to fill the U100 syringe to the 2.5 mark. This is to get 0.025 milliliters of U40.

    You are still giving 1u of U40 insulin -- just using a different "container" which is smaller.

    If you change to U100 insulin, you will keep the same REAL dose of 1 unit of insulin (this is my example dose)

    If you give 2.5 units of U100 insulin when your kitty really only needs 1 units, you will be giving an OVERDOSE.

    So -- be very careful when using a conversion chart.

    If using U40 insulin in U40 syringes - NO CONVERSION CHART
    If using U100 insulin in U100 syringes - NO CONVERSION CHART

    If using U40 insulin in U100 syringes - CONVERSION FACTOR = 2.5x
    NEVER use U100 insulin in U40 syringes - NEVER EVER -- a sure trip to HYPO LAND
  3. sweetcherrypie

    sweetcherrypie Member

    Jul 18, 2010
    Thank you very much for all that info it is most reassuring :smile:
    Carol and carbonel
  4. Mary & Stormy Blue

    Mary & Stormy Blue Member

    Dec 29, 2009
    If you are using u40 insulin in a u100 syringe, you are not actually giving MORE insulin. You are giving the same amount of insulin by VOLUME.
    It is rather like saying 1 ounces (US, fluid) is equal to 1.04 ounces (British, fluid). They are the exact same amount of fluid - they are just measured differently.

    u100 syringes also tend to be thinner than u40 syringes. The unit marks are closer together on a u100 3/10cc syringe than they are on a u40 5/10cc, If you were dosing, oh, say 1 unit of u40 insulin and you pulled 1 unit of u40 insulin into a u40 syringe, and then pulled one actual unit of u40 insulin into a u100 syringe, (that would be to the 2.5u mark on a u100 syringe), and then you measured the VOLUME of that insulin, you would find that it is the exact same volume of insulin REGARDLESS of which syringe you are using.

    Conversion chart links - u40 insulin in a u100 syringe ... Chart.aspx

    The best thing about using u100 syringes to dose u40 insulin is this:
    You can fine tune doses SO much easier with u100 syringes because many of them come with half-unit markings,
    they are readily available at ANY pharmacy, and, they are less expensive than u40 syringes.

    Having said all that, it is NOT recommended that you ever dose u100 insulin in a u40 syringe.
    Because u100 insulin is more concentrated, and u40 syringes are not as well calibrated,
    you could easily overdose your kitty on insulin were you to reverse the conversion formula.
    NEVER use u100 insulin in a u40 syringe. NEVER!!

    As far as regulating your kitty on Vetsulin, I don't think it is going to happen. Is your vet aware that the manufacturer is asking that it no longer be used due to the fact that it is not working properly? Are they aware that the US FDA has issued warning against using this insulin? The manufacturer is even requesting that veterinarians place their patients on another kind insulin because Vetsulin is not stable from dose to dose - batch to batch. If your vet is refusing to change insulins after knowing this issue, it is time to change vets. (S)he is asking for a malpractice suit to happen. My suggestion would be to go to these links, read the available information, print them out and hand carry them to your vet and DEMAND a different insulin. If they do not comply - kick that vet to the curb and find one who will. ... 188752.htm

  5. Katie & Mego (GA)

    Katie & Mego (GA) Member

    Mar 15, 2013
    If anyone needs confirmation of what is explained in this board, see the following information

    Mego was Rx'd 1 unit of U100 Insulin (Lantus) twice daily every 12 hours.
    The vets office gave me U40 syringes with U100 insulin without telling me the difference.
    Day 1 numbers came down nicely
    Day 2 - No AM shot because I couldn't get an AMPS / PM shot 1 unit in U40 syrings (2.5 times the dose of 1 unit in a U100 syringe) Fast track to near Hypo land.
    Day 3 - Gave .75 units because of previous nights crash and AMPS. Within 3-4 hours we were in Hypo land again. Late evening, I discovered the problem of overdosing with the U40 syringe.
    :twisted: :twisted: :twisted: :twisted:

    I thought those with degrees were supposed to know the difference!
    THANK GOD FOR FDMB - because I probably would have killed my Mego if I had blindly listened to the vets dosing instructions. Knowledge is power!
  6. Elizabeth and Bertie

    Elizabeth and Bertie Well-Known Member

    Sep 6, 2010
    ~ Bumping very old thread because of discussion on using conversion chart. ~

    Mary Ann @Tuxedo Mom - Yes, interesting thread. And utterly 'brain frying'... :confused:
  7. Tuxedo Mom

    Tuxedo Mom Well-Known Member

    Dec 2, 2014
    Thank you Elizabeth. This issue came up on FDMB FB yesterday and is really a brain twister. However some information I found about using U100 INSULIN with a U40 SYRINGE . Usually it is the reverse that people do but there is some confusion about this.


    As you see in the picture a U40 syringe uses 2.5X as much VOLUME of insulin to make up 1 unit as compared to a U100 for the same dose. This is why when people use U100 syringes with a U40 insulin they need to draw up 2.5X as many units, since the volume in a U100 is smaller per unit.

    From the Vetsulin website:

    " " If a client uses a U-40 syringe or VetPen with a 100 IU insulin preparation, they would be injecting two and a half times the amount of insulin necessary, which could result in fatal hypoglycemia." "

    U40 1u = 1 ml/ 40 = 0.025 milliliter

    U100 1u = 1 ml/ 100 = 0.01 milliliter

    So the unit line on a U40 syringe contains more physical volume than the same unit line on a U100 syringe, meaning that 1 unit of U100 insulin measured on a U40 syringe would be 2.5X more than if measured on a U100 syringe.

    So in effect, using a U40 syringe with a I100 insulin would actually be giving 2.5X the dose. On the FB page a lady is using 1 unit of Lantus with a U40 syringe which would mean she is actually giving 2.5 units of Lantus.

    This combination rarely comes up but it is important to understand the differences.
    Last edited: Aug 21, 2017
  8. Elizabeth and Bertie

    Elizabeth and Bertie Well-Known Member

    Sep 6, 2010
    Thank you for this, Mary Ann.
    It is a baffling subject, so it's good to see this so clearly written.
    Tuxedo Mom likes this.
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