I get some great questions from clients. They inspire me with article ideas and keep me in tune with diabetic pet owners. I enjoy interacting with our readers, and sometimes the questions are worthy of a newsletter. I bet if one person has this question and takes the time to write me, there are likely lots of folks with a similar question. Today’s question is what is the best time to check blood glucose after an insulin injection.

Doctor, what is the best time to check the blood glucose for our Insulin dependent beagle after an insulin injection? Is it a good idea to give less insulin at night and more in the morning? Our beagle crashed on Sunday, had a seizure and spent the day at emergency vet hospital. She then spent Monday at her vet’s office. Her insulin has been changed from Humulin N to Vetsulin. Polly has been so erratic for three years. Do you feel she will do better on Vetsulin?? We are worried, tired and broke!!

I’m so sorry you and Polly had this experience. Hypoglycemia is scary, and I’m glad you were home to identify it and get her to immediate care. It was no doubt an expensive and worrisome weekend!

Now on to your questions:

I prefer equal dosing every 12 hours as the norm. I also recommend equal portions for the morning and evening meal. Consistency is your friend! I would feed equally portioned meals and give equal doses of insulin at the time of the meals, every 12 hours. Of course if the blood glucose is low you might wish to back off for the dose and consult your vet. After a hypoglycemic episode, we nearly always lower the insulin dosage and increase blood glucose monitoring. Since you’ve changed insulins, it would be harder to evaluate what a “lower” dose might be. When starting insulin or changing to a different type of insulin, I advise folks to start low and then sneak up on the insulin dose.

Vetsulin and Humilin N have pretty similar duration of effect, but each pet will respond to a particular insulin differently. Some pets may absorb a particular insulin better than other pets. Some may metabolize a particular insulin faster than other pets. It’s hard to predict how your pet will do with the insulin change. Before changing insulin, I like to make sure we are doing our best with other aspects such as feeding and curves and consistency in general. Levemir might be a good choice if you don’t find improvement with Vetsulin as it tends to last longer than Humilin N or Vetsulin in most dogs.

As far as a “best time to check” blood glucose, I’m not a big fan of spot checks unless you think your pet is acting funny (i.e. hypoglycemia or hyperglycemia). In general, I’m a much bigger fan of running blood glucose curves. That’s when we check the blood glucose every 2 hours from one insulin dose and meal until the next insulin dose and meal 12 hours later. I put in a special twist as well: if the blood glucose drops below 150 mg/dl I like to check it hourly until it starts to rise again. This way I don’t miss where it bottoms out. A blood glucose curve tells us how long insulin lasts in your pet, and also helps us decide if we should increase or decrease the insulin dosage based on where it bottoms out. We want to run a curve on an “average” day. Don’t run the curve when you have former college buddies are visiting or when there is noisy construction work going on outside your home or when your crazy aunt is visiting and you know she sneaks your pet food. We want to run it on a day that is your pet’s “norm”. We run blood glucose curves a few times each year, even when we think we have a pet under good control in case the insulin requirements have changed a bit, so we can tweak the dosage and get the best regulation possible. Or, if we’ve altered the insulin dosage, we will check a curve 5 to 7 days after the dose change to see if we’ve improved the situation.

Now, if you have a pet with chronically erratic blood glucose numbers or a finicky appetite, I’ll sing a different tune. Some pets are difficult to regulate and will need to be checked before each insulin dosage. Folks doing “tight glucose control” on their cats, which offers the best chance of getting a cat into diabetes remission, will also check blood glucose prior to each insulin dosage.

In general, doing a spot check 6 or 8 hours post insulin injection to assess dosage is very “old school”. I know some vets used to assess insulin dosage based on a single number, but it is just that, a single number. We use curves to assess glucose control. Or sometimes we use A1C levels or fructosamine levels to assess control when a pet has erratic blood glucose numbers. Still, blood glucose curves yield more information than an A1C or fructosamine levels. And curves are significantly less expensive when run at home than these other tests.

Have a question or comment? Post below or email me at joi.suttondvm@adwdiabetes.com. I always enjoy hearing from my readers!


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

Dr . Joi Sutton

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.
Dr . Joi Sutton

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