Do You Shake or Roll Insulin?

By Dr . Joi Sutton|2023-09-25T10:37:05-04:00Updated: March 16th, 2017|Pet Care, Pet Diabetes, Pet Newsletter|12 Comments
  • Cat being examined by a doctor

When I was in vet school many moons ago, they taught us that shaking insulin could inactivate the particles. We were taught to gently roll the bottle between our hands to suspend the particles. The story has changed a bit since. The package insert for Vetsulin now actually recommends shaking the bottle. This wording was new when Vetsulin came back on the market. Some insulin, such as Glargine, apparently doesn’t need mixing at all.

Mostly, I’d still recommend rolling most insulin bottles. If in doubt, roll it. Why does this matter?

A few years ago I met a pet owner who didn’t mix the insulin before giving her pet an injection. She was essentially giving the fluid that suspends the insulin, but the insulin particles sat at the bottom of the vial. It only makes sense that the stuff at the end of the vial would then be more concentrated than the fluid when the bottle is new if it isn’t properly mixed. Her pet had been diabetic for a few months when I met her, and she was frustrated. Talk about lack of diabetes control if you somehow didn’t know to suspend the particles of insulin. We throw so many facts at clients when we first diagnose a pet as diabetic. I can see how she missed this simple step. This is why I sometimes ask pet owners to come into the clinic to show us how they perform various diabetic-related tasks if we don’t achieve good diabetic control. Never be offended if your vet wants to witness your technique – whether that is giving an injection, pulling up the insulin, or even checking a blood glucose. We do this for a living and could possibly catch such an error.

NPH and lente and ultra lente insulins should be mixed before each administration. Vetsulin should be mixed well, particularly the first time it is mixed. The insert says “shake”. Somehow, I just can’t wrap my brain around shaking a bottle of insulin, but the manufacturers of Vetsulin thinks it is fine to do so. They know best. It’s their product after all. NPH should be gently rolled or inverted repeatedly until the particles are evenly distributed. Both Vetsulin and NPH look milky and homogeneous when properly mixed.

One possible downside of shaking an insulin could be incorporating air bubbles which would make the amount of insulin given to the pet less than desired if part of the volume was air. I read online the following advice regarding Vetsulin, “Don’t over shake it and don’t under shake it.” Gee, that’s helpful. I think I’d probably stick with the good old fashion techniques we’ve used for decades.

Ways to mix the insulin:

    • Roll it between your hands about 20 times until it is evenly suspended.
    • Invert it end over end about 20 times until it is evenly suspended.
    • Hold it in your hand and move your hand in a ‘figure 8’ sign about 20 times until it is evenly suspended.

If in doubt, mix it. Personally, I’d stick with a gentle roll or inversion over shaking to avoid air bubbles in the insulin.

Have a question or comment? Post below or email me at [email protected]. I always enjoy hearing from my readers!

NOTE: Consult your veterinarian first to make sure my recommendations fit your pets special health needs.

About the Author: Dr . Joi Sutton

Dr. Joi Sutton is a 1993 graduate from Oregon State University. She has practiced both in emergency medicine and general practice. Dr. Sutton has done extensive international volunteer work though Veterinary Ventures, a nonprofit organization that takes teams of veterinarians to undeveloped countries for humane medical care. She also runs a small animal practice in South Florida. Connect with Dr. Joi on LinkedIn


  1. Elaine November 16, 2021 at 11:59 pm - Reply

    My on cat is at the emergency vet his reading was about 20 when we brought him in. My friend who fills in when I am away assured me he only got his 4 Marks of pzi I think it’s called. He was in extreme distress. They spent hours with glucose drips trying to regulate him. He hasn’t had insulin since yesterday and now his numbers are high again. But the strange thing is his brother who is also on insulin for 3 years now just tested tonight with number of 22! So I got some dry food in him it went to 32. I then got honey in a syringe and got him to 47 and will give him more honey very soon. But all this to say my question is could the fact that I am at the bottom of the vile have become super concentrated and thrown them both into these severely low numbers? I always roll the vile to mix before use.

    • Dr . Joi Sutton November 21, 2021 at 9:15 am - Reply

      Yes, that is possible for some insulins. Some insulin types yo7need to roll to mix. Some you don’t need to mix at all. And Vetsulin you need to shake well. It depends on the type of insulin if it could concentrate Attlee d of the vial. I’m glad you have a home glucose meter to check and be aware of your other kitty’s glucose levels. Good job! Do chat with your vet.

  2. Denise Kowalski November 7, 2021 at 2:07 pm - Reply

    Hi. I use vetsulin for my dog. Is it ok to mix what’s left in The old bottle to the new bottle?
    I did it this week. Just want to be sure it’s ok
    Thank you

    • Dr . Joi Sutton November 8, 2021 at 7:01 am - Reply

      No, do not mix the contents of the old bottle into the new bottle. One of the concerns for any injectible is that we could introduce germs into it by repeat punctures with needles, this is why you should never touch the port of the bottle with anything but the fresh needle itself. Keep a cap or something to protect the port of the bottle! Finish one bottle then start the next bottle. Great question.

  3. Anonymous December 10, 2019 at 8:26 am - Reply

    I dropped my vetsulin. is it bad now?

    • Dr . Joi Sutton December 16, 2019 at 8:29 pm - Reply

      So long as the bottle is not broken it should be fine. 🙂

  4. Amy March 25, 2019 at 9:32 pm - Reply

    Very helpful, thank you! Keep dropping vial just onto counter, so I keep buying new vials. Was terrified that I ruined it and was going to end up in the poor house.. Now I’m just broke. Lol

    • Dr . Joi Sutton March 31, 2019 at 7:08 pm - Reply

      Some insulins come in pen form, such as levemir, Vetsulin, and glargine. At least when you drop a pen the vial doesn’t break. Additionally, pens contain a smaller volume so for small pets less insulin goes to waste by the time you should discard a 10 cc vial. That is, assuming you don’t break the vial by dropping it. The makers of Vetsulin now advocate shaking the insulin before administration.

  5. FRANCES MUNSCHAUER May 2, 2018 at 12:52 pm - Reply

    I appreciate your response..I do not have a DVM that is familiar with levemir but bought a vial recently but have no protocol or guidance to utilize it. I cannot find a DVM that supports it..even at MSU. I see no predictability with Vetsulin and do worry about the shaking-but we do it. I know that every dog is different but with no change in diet, exercise or get 73 FBG before meal and 73 2 hours after vs 3-400 other predictable nadir make..However, the warnings of levemir on 5 kg dog are worrisome. I am now researching everything: Some DVM’s believe that vigorous shaking an damage the particles? Does particle size differences via 30 gauge needle hinder delivery of either particle..since the crystalline portion is less predictable and also does not last past 8 hours. Merck is not helpful and offers the owners’ DVMs’ who learns from reading the Vetsulin insert. I guess more intensive research is not a priority yet. It would be great if DVM’s or dog owners would publish some information, their charts, curves of dogs that have been treated with cat people do on the cat forum.

    • Dr . Joi Sutton May 21, 2018 at 11:43 am - Reply

      Merck now tells clients to mix Vetsulin well. Do what the manufacturer suggests. I don’t choose Vetsulin often. My go to insulin for dogs at my small animal general practice is levemir, but levemir is so potent in dogs it would be difficult to dose for a small dog. Dogs are very sensitive to levemir, about 4 times more sensitive to levemir than to Vetsulin or NPH. Levemir cannot be diluted. Even with a 3/10 cc syringe with half unit markings it can be difficult to measure such a tiny dose.

  6. FRAN MUNSCHAUER March 16, 2018 at 1:36 pm - Reply

    I spoke several times with Vetsulin experts? that claim “You should vigorously shake it”..My concern was, could shaking it like shaking a can pf paint at Lowe’s, damage the crystalline portion making the longer lasting portion less effective. they simply said, “No”..I don’t trust this answer and am seeking more info on this “shaking”..may switch to Levemir. Suzie 5 kg charts NPH, Lantus, Vetsulin (vigorously shaken).

    • Dr . Joi Sutton March 18, 2018 at 10:24 pm - Reply

      Apparently Vetsulin is to be shaken. For years we were told not to shake insulin, but the company says to shake it… so shake it.
      I strongly prefer levemir over Vetsulin and NPH for dogs. Vetsulin and NPH don’t last as long as levemir. Know that the levemir dose will be less than the Vetsulin dose as dogs are very sensitive to levemir.
      🙂 Joi

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