Health

Blood Glucose Curves Help Keep Diabetic Pets on the Straight and Narrow

Being regulated lets the kidneys do a happy dance

October 10, 2016 (published)

blood glucose curve Oursler

The results of a blood glucose curve. Photo by Dr. Teri Ann Oursler
Diabetes is not one of those diseases that you get to set it and forget it; it requires constant monitoring and evaluation of the insulin dose to give us control of the disease and decrease its symptom and side effects.

After a few decades, people with unregulated (uncontrolled) diabetes tend to end up with retinal problems, blood vessel damage, kidney problems, etc. Because of their shorter life spans, dogs and cats with unregulated diabetes don’t usually face the same long-term consequences it causes in human diabetics. Normally their short life spans cause us grief, but in the case of a diabetic sometimes that short span can be a boon.

Pets who are unregulated diabetics will have symptoms that can be irritating, like urinating frequently (“I want in, I want out, I want in, I want out…oh hey, can I come in now?”) or urinating in inappropriate places, such as your new couch or your bedroom pillow. They also can have symptoms that threaten their health, like too much weight loss.

Our primary goal with diabetic dogs and cats is to give them a good quality of life: their body weight is stable, they don’t have to hover over the water dish all day, and their potty habits are normal in that they prefer to pee outside rather than on the couch.

Accurate monitoring of your pet's diabetes can help to maintain a good quality of life for both you and your pet. After all, who wants to curl up and watch a movie on a pee-soaked couch?

Exactly how does monitoring help us to accomplish this higher quality of life? By regulating their blood sugar (glucose) levels.

Normal blood glucose levels in dogs and cats are similar to those in humans, about 80-120 mg/dl (4.4-6.6 mmol/L). Animals whose blood glucose levels are in this range will look and act normal.

Fortunately for us, they will also act mostly normal if their blood glucose levels are as high as 100-250 mg/dl (5.5-13.75 mmol/L). We find that if we can maintain that level for as much of the day as possible, the pet will act pretty normal, with an acceptable amount of drinking and urinating (in the right places!), and stable body weight without becoming supermodel thin.

When the blood glucose levels are higher than 250 mg/dl (13.75 mmol/L), the kidneys are not able to keep the glucose from being lost in the urine; the glucose that is lost in the urine swoops water out with it, so the pet will drink a lot of water to keep up with what is being lost in the urine.

In general, that is our mission: keep the pet regulated so the kidneys can continue doing a happy dance while filtering out the stuff that needs to be removed. Nonetheless, we also have two other goals:

  • To keep the dog or cat from having episodes of hypoglycemia (low blood glucose), which can lead to seizures and brain damage. 
  • To reverse diabetes in cats when possible. Within the first 6 months after diagnosis, we want to keep a cat’s blood glucose levels as close to normal (80-120 mg/dl (4.4-6.6 mmol/L) as possible, as most cats have type 2 diabetes. Because they still have their own insulin, if we take immediate steps to turn around the factors that are creating resistance to their own insulin, we can make their diabetes go away in about 70 percent of cats, like a genie stuffed back into the bottle, if the following steps are also taken: 
  • Reduce the cat's weight 
  • Switch to all-canned, low-carbohydrate diet 
  • Use an insulin that works well throughout the day 
  • Continue to aggressively monitor to keep their blood glucose levels as normal as possible.

Now we’re ready to talk about monitoring. There are several options used:

  • A single blood glucose level 
  • A fructosamine level (a compound that reflects all the blood glucose levels that the dog or cat has had for the prior two to three weeks) 
  • The amount of glucose in the urine (which is measured on a dipstick as a color change and is estimated as 1+ for a low amount of glucose and 4+ for a large amount) 
  • Blood glucose curves, a series of blood glucose measurements done between the morning and evening insulin doses and meals.

What’s the difference between these methods? Why can’t we just do something simple, such as get a single blood draw for a fructosamine level or a single blood glucose level?

It’s like this: If we see a single high blood glucose level (say 350 mg/dl (19.25 mmol/L), or an elevated fructosamine level, it is human nature to interpret that in only one way: my pet needs more insulin.

However, we can see a high blood glucose or a high fructosamine level (or lots of glucose in the urine) when the pet is overdosed as well.

Yeah, that’s kind of confusing.

When blood glucose is too low, hormones such as cortisol and adrenalin rush right out of the cells to try to save the body from dying of low blood sugar. They do this, in part, by stopping the action of the injected insulin and causing the liver to release glucose. Thanks to these actions, however, the blood glucose swings wildly high in response to the injected insulin. If you measure the blood glucose levels later in the day, you’ll find them to be high. However, if you’ve only measured a single blood glucose at that time, you have no way of knowing that they’re high because there was too much insulin injected earlier in the day, or not enough insulin, so you’re inclined to give more, which just makes the problem worse.

Blood glucose curves are one way veterinarians can monitor your pet's diabetes. A blood glucose curve is a graph of blood glucose levels over time. This graph helps to establish the type, dose, and frequency of administration of insulin.

The other problem is that a single blood glucose or fructosamine level (the amount of glucose in the urine) tells us nothing about the kinetics of this insulin for this particular pet. Kinetics, meaning how this drug works in this individual animal, refer to how long the insulin lasts after each injection and how long it takes after each injection for the insulin to start working. You know, the small details that make the difference between a diabetic’s good day and a bad one.

Problems with kinetics can’t be fixed by changing the insulin dose: they can only be fixed by changing to a different kind of insulin, and the sooner we figure that out, the less time we waste trying to use an insulin that just doesn’t have the right kinetics for that particular pet.

So how do we do a blood glucose curve?

Because we’re trying to mimic what happens at home on a normal day, it’s best for the dog or cat to have their food and insulin injection at home the morning of the curve, then get dropped off at the veterinary hospital within an hour or so to start the curve.

Blood is collected every two hours throughout the day, changing to once-an-hour if the blood glucose levels are dropping to lower than 150 mg/dl (<8.75 mmol/), to ensure we don't miss an episode of potentially dangerous hypoglycemia.

Blood glucose curves can also be done at home, which can mean less stress for both owner and pet, and can result in a significant cost savings. It’s a good idea to get advice from your veterinarian about which glucometer brands are likely to be accurate. Some really are not accurate, and bad data is worse than no data.

Even a brand that tends to be reliable should be checked at the beginning for accuracy of that individual machine. To do that, have the first blood glucose curve done in the veterinary hospital, so they can check your glucometer against the hospital glucometer many times throughout the day’s curve.

Once it's established that your glucometer is reliably accurate, then they teach you how to collect the sample (the inside of the upper lip is an excellent site for dogs, using a lancet; in cats it's easiest to use the outer margin of the ears). Wherever the sample is collected, it is important not to ‘milk’ the site while trying to get a big-enough drop for the glucometer, because milking it to get a big-enough drop for the glucometer alters the blood glucose result and there is no reason to get bad data.

If you are generating the blood glucose curves in the comfort of your own home, so your dog can pee on the couch rather than in the car, it's important to share the results with your veterinarian. Your vet is trained to interpret it. Let your veterinarian make the decisions on adjusting the insulin dose for the sake of the couch and your pet.

While blood glucose curves are not foolproof, they give us the most accurate picture of how high and how low the blood glucose levels go during that day, how long the insulin is lasting, and how long it takes for the insulin to start working after each injection. Because the curves fluctuate from day-to-day, it is not possible to use one day’s curve to predict when to take a single blood glucose to ‘catch’ the lowest or highest blood glucose on a different day.

How often should a blood glucose curve be done? In a newly diagnosed diabetic, running a blood glucose curve once a week is recommended, then adjust the dose based on the results. It is important to wait a week after each dose change before running the next curve. Once the pet is regulated, then we can back off a bit and run the next curve in three months, or sooner if they develop symptoms of diabetes again (drinking too much, urinating too much, or losing weight).

In a newly diagnosed cat, however, where we're really hoping for the diabetes to go away, we run the blood glucose curves weekly while controlling the factors that cause insulin resistance. As the diabetes begins to resolve, the dose of insulin is decreased and decreased, until finally, the insulin can be stopped. We know cats in which the diabetes resolved within the first week of treatment with insulin and a canned low-carbohydrate diet, so careful monitoring is essential.

Blood glucose curves are best used as a more complete view of what THIS insulin is doing in THIS animal on THIS day. When that information is combined with the animal’s clinical picture ― how stable the body weight is, how much drinking and urinating is going on ― that helps us give your diabetic dog or cat, and your couch, the highest quality of life we can for as long as possible.

22 Comments

Colleen Whillans
August 15, 2020

My cat will be 13 in September. He was diagnosed with diabetes in March 2017. It took from then to July 2018 to get the right dosage of insulin. From July 2018 til July 23rd we had the right dosage. He is on Prozinc, Diabetic dry vet food. He was 14 pounds when diagnosed. Now he is 17.7lbs. So didn’t gain much. So after taking my cat to the vet to have his yearly check up they noticed his Blood Glucose level was 16.6. So they adjusted his insulin. So he went from 4 ml in the morning and 3.5 ml at night to both 4 ml morning & night. Was out camping August Long weekend and did his blood count July 28th. It was low 3.5. So called the vet and they dropped his dosage to 3.5 morning & night. I took it again July 31. One was 2.9 and the other was 4.3 two hours later. So vet knocked it down to 3 ml morning & night. Did another count August 11th and it was still low. So vet told me to drop dosage to 2.5 ml morning & night. I am hoping we can get his insulin stablized again. He still acts like a kitten. But he does have A little bit of cataracts but I am hoping to keep him around longer then 13 years.


Jackie
August 14, 2020

My Maltese is eight years old. I have been trying to keep the glucose at a balance level but it’s a little hard to do that today I took a glucose it was 112 how much insulin should be given for that level in the 100’s.


Robert
August 8, 2020

Liked the article.  It was informative. I have an elderly cat that just turned 17.  She's been diagnosed diabetic going on 4 years, and tolerated the insuln well. Two weeks ago she went in for annual visit and her Doctor discovered low b/g levels and recommended taking her off insulin. A week ago, I noticed she wasn't able to stand or walk on her own.  Took her to the hospital and she had b/g levels of 345.  Gave her 2 units and 1 unit later that night.  In addition to a 250 ml IV drip.  Seen the next day and b/g levels were 74.  Continued the IV fluids with no insulin until morning, and b/g levels swung back to 174.  It's gone like that for six days running.  Her blood glucose levels won't stabilize.  Have fed her slurry with syringe all week and her appetite is coming back slowly.  She is rehydrated as well.  Still not strong enough to stand or walk on her own.  But she's alert and responsive to her surroundings.  Any thoughts?


Angela G.
June 30, 2020

My sweet beautiful cat was on Vetsulin for 5 years. I could not monitor her blood sugar. It was too stressful for her and me, so my vet put her on 2.5 units 2x day. She was doing great every day I never saw any symptoms and then OUT OF THE BLUE she had a Hypoglycemic episode where her sugar went down to 20. I rushed her to the vet and they got it under control. She was doing so well but the morning I went to pick her up she had another one and no one was at my vets office overnight to save her. They tried but too much damage had been done and she didn’t make it. I am devastated by this. I’m waiting for my vet to call to give me some answers.  How could another episode happen So suddenly when she was doing so well again?


Beth DeVinney
June 15, 2020

Great news for pet parents of diabetic dogs! Free style libre!  We have been monitoring our dog Gracie since last November and it is fantastic.    She was diagnosed after going blind over night from cataracts. Purdue University allowed us to use the libre monitor and she is in a study there for her eyes As well.  She gets shots twice a day and it works really well she is 95% regulates.


Fran Munschauer
May 30, 2020

Suzie 10 lb chihuahua on insulin 3 years and has OPPOSITE of "Dawn phenomenon" as in humans. BG 500 at dinner...250+ IN AM..SHE REMAINS ASYMPTOMATIC BUT has had ERRATIC BG LEVELS ON Vetsulin,especially at dinner time...doesn't last 12 hours OR may suddenly work overtime with AM BG 80??? NPH didn't last..Lantus was good except I never slept worrying about 4 am hypoglycemia...I wanted to try a HUMAN insukin (Novolin 70/30) hoping it was better FDA regulated but no DVM uses it. Suzie has had her first medical issue-refused to eat- but resolved next day and chem panel was fine except Hct 24. DVM suspects stomach issue??? My main question is WHY would her BG be 500+ at dinner but 300 or so in AM? Suzie's spreadsheethttps://docs.google.com/spreadsheets/d/1O1YNDHz-t4REns_tbAN6D_M3AYT6_kgqbHE7JWo6kSM/edit#gid=811447094:


Hilary Rockwell
May 25, 2020

My mom has a 13 year chihuahua that has diabetes and the vet has him on 4 units of insulin in the morning and 3 in the evening but his sugar is still 350 to 400 and they can't get it down :(


Christy Corp-Minamiji. DVM
March 22, 2020

Hi Charlene,  I'm so sorry you're having this struggle. Managing diabetes can be such a pain!  Unfortunately, the only way to get a handle on it will be to work closely with your veterinarian. 


Charlene Kendrick
March 22, 2020

My Buchon is 14. For the past three years we have been giving her insulin twice a day! She started off with a 4 then a five! But since I check morning and night I usually give 5 in the morning and if necessary 6 at night! I have dropped down to 4 if she is low! Tonight she was HI. I guess that means as high as she can go! I do not know anything else to do! They can change her insulin but they said it would cost a lot! Help!


Jennifer
March 6, 2020

My 10 year old terrier was diagnosed 7 weeks ago, is on Vetsulin. He started at 3ml and has been increased to 9ml. He is still not regulated, with very high levels in the morning (~650) before his shot and levels around 350-450 in the afternoon. When he was first increased this last time, he had levels in the 100's, but it only lasted a day. I was told by some folks on the Facebook support page that because my Vet increased more than 0.5ml at a time - she increased 1.5ml (from 6.5 to 8) one week and 1ml (from 8ml to 9ml) the next week, that the optimal dose could have been "missed," as though there's a rebound affect. Is this true? I sent my Vet glucose curves, and I believe she increased based on the fact that the lowest levels were still very high. I've read about the Somogyi affect, but I don't think it applies here since the levels never went lower than normal and then spiked up within a day. I do believe that the Dawn affect may apply, but what I really want to know is whether there's some sweet spot number that when missed (increased beyond that number), will cause a dog to stop responding to the insulin altogether.  Thank you!!


Holly
January 18, 2020

Great info! I want to share for other diabetic pet parents. Ask your vet to write you a script for the Style Libre. Our dog has been wearing it for 16 days (second sensor now). It is non surgical and can be applied in about 10 min. You can download the app or buy the coordinating reader at the pharmacy. You can then scan the sensor AND GET AN ACCURATE READING. Our dog has no issues with it. He sleeps wearing it, can be bathed etc. it is amazing. We are able to check his sugars anytime we want and no need to prick him. Without insurance it’s $60 ish dollars for 14 days of tracking. Also, if you are having trouble with using an alpha tracker here is the way to get the blood you need. Insert the lancet into the one thing. Take the cover off lancet. Expose needle tip. Very gently PULL THE LANCET OUT a little bit. (This allows the needle to actually prick the dogs ear!) put the cap back into the pen. Warm up your dogs ear with a warm rag. Massage ear gently. Once the ear looks a little pink, then hold the ear gently against the pen and click the button for the lancet to come out. Flip that ear back and give it a few seconds. You should get enough blood to test. If not gently squeeze ear for blood to bubble.


Christy Corp-Minamiji, DVM
November 26, 2019

Flash glucose monitoring devices such as the Freestyle Libre device mentioned by Z are fairly new.  Here is a link to an article on our sister site Veterinary Partner that explains more about these devices. https://veterinarypartner.vin.com/default.aspx?pid=19239&id=9150771 


Z
November 24, 2019

My doc implanted a temp (lasts 14 days) glucose monitor in the back of my pup's neck. It interfaces with an iphone app called FreeStyle LibreLink. Try it out. It's more convenient than dropping off at the vet. Saved tons of money, but the app is still buggy. Works 90% of the time.


Tani
October 27, 2019

My dog was diagnosed 4+years ago. She is practically blind. We have managed to control her levels most of the time. The last few days her levels have been around 7 and too low to give insulin. Will this be damaging to her not to have insulin.


Michelle Massotti
October 22, 2019

I'm a new mom to a diabetic dog. I purchased an alpha tracker and had a miserable/anxiety day of err codes all day. 10 Lancers and 6 strips with not one reading. I cant afford $107 at the vet for a curve.(we just saved her from ketoacidosis and wiped us out) will the dosage I'm giving her now ever be reduced? (which seems gr8, cause she's eating and drinking and urinating normally) I'm giving exact food and insulin at exact times to help from any fluctuations. 


Christy Corp-Minamiji, DVM
September 11, 2019

Hi Diana, Unfortunately, diabetes can be challenging to control for many patients.  Also,there are so many factors at play that no one other than a veterinarian who is working with you and your dog is going to be able to assist.  We recommend making an appointment to go through all of your records and concerns with your veterinarian.  I'm sorry you're having such a rough time getting her blood glucose under control. 


Diana Gibbs
September 10, 2019

My dog was diagnosed in Feb this year. We have been doing blood test on her every 2 hours and her blood is so unpredictable. Our vet keeps changing us on her doses and I have been keeping very good records on her. with a higher dose she goes too low and with a lighter dose she is too high. Please help !


Deb Domurat
February 15, 2019

So if your cat's level has been in the mid to high 300's for several checks he should be a insulin?  I knew when my other cat needed it it was over 500, but this cat is up and down :-(


Gus Ray
May 30, 2018

Great article, also of note is A1C for cats and dogs is now available as a test to veterinarians


Tania
April 14, 2017

Thanks for the great article. My sentiments exactly (albeit phrased in a more eloquent way). However, not so good when your boss tells you that you're not giving enough injections.


Julia Dahlke
March 23, 2017

One of most oft-prescribed treatments:  "tincture of time".  It's been around a long time but very effective.  Thanks for the article!


Kate McDuffee
March 23, 2017

A mentor of mine, regarding watchful waiting or benign neglect, used to say, "Don't just do something. Stand there!"



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