Glucose curves at home, step by step, for cats and dogs
This guide is general information and not a substitute for your veterinarian. Run curves the way your vet asked, and never change the insulin dose on your own based on the numbers.
A blood glucose curve is one of the most useful tools for getting your pet's insulin right, and doing it at home is often better than at the clinic. The short version: on curve day you feed and give insulin exactly as normal, then take a small blood sample at set times across the dosing interval, so your vet can see how the blood sugar rises and falls, how low it goes, and when. That pattern is what a dose is set from.
Below is what the curve shows, why home usually beats the vet's for this, what you need, how the day goes, the mistakes that quietly ruin a curve, and how to hand your vet something they can actually read.
What a glucose curve shows, and why home is often better
A single blood sugar reading is a snapshot. A curve is the film: it shows how the level moves through the hours after a dose, where the lowest point (the nadir) falls, how low it gets, and how high it climbs before the next dose. Your vet uses the shape to judge whether the amount is right, whether the insulin lasts long enough, and whether the timing fits your pet.
Home usually beats the clinic for one big reason: stress raises blood sugar. A car ride and a day in a strange place can push the numbers up, especially in cats, so a clinic curve can read higher than your pet's real day. At home, with normal food, normal routine, and no stress spike, the curve reflects ordinary life, which is exactly what your vet wants to dose for. It also spares your pet a long, tiring day away.
Why this matters more for cats
Cats are the reason home curves became standard practice, and it's worth knowing why, because it changes how you read the numbers.
Stress raises blood sugar in any animal, but cats are the extreme case. The carrier, the car, the waiting room, the smell of other animals: a cat can arrive at the clinic with a blood sugar well above where it sits at home, and stay there all day. Vets call this stress hyperglycemia. It isn't the cat's diabetes getting worse, it's the morning the cat has had. The trouble is that a curve run on that cat, on that day, looks like a cat who needs more insulin. Dosing up from a stressed curve is how a cat ends up with lows at home.
This is also why your vet may check a fructosamine level alongside curves. It reflects the average blood sugar over the preceding couple of weeks rather than this hour, so a car ride can't move it. If a clinic curve looks high but the fructosamine looks reasonable, stress is usually the explanation, and your vet weighs the two together.
None of that means a clinic curve is wasted. It means a home curve on an ordinary day is usually the truer picture for a cat, and it's why your vet may ask you to run them yourself. Dogs are less prone to the stress spike, so the gap between home and clinic is smaller for them, but the same logic holds: a normal day gives a dose you can actually live with.
Equipment and setup
Your vet will set you up and show you the first sample. Typically you'll have:
- A glucometer. Ideally a pet-specific one, or a human meter your vet has approved, since pet and human blood read differently.
- Test strips and a lancing device with fine lancets, in the setup your vet showed you.
- A warm spot to sample from, usually the edge of an ear or a paw pad. A warm ear bleeds a small drop more easily.
- A log sheet, or a note on your phone, to write down each time and reading as you go.
- Treats and patience, so sampling stays a calm, quick thing.
Some vets now use a continuous glucose monitor, a small sensor worn on the skin that reads levels automatically for days. If your vet suggests one, it can make curves far easier. Either way, the plan comes from your vet.
How the day goes
The golden rule of curve day is to change nothing except adding the sampling. A curve is only useful if it reflects a normal day.
- Feed and dose exactly as normal. Same food, same amount, same time, same insulin. Note the time of the meal and the dose.
- Take the first sample as your vet directed, often around the time of the dose, to mark the starting point.
- Sample at set intervals across the dosing period, commonly every couple of hours, right through until the next dose is due. Write the time and reading each time.
- Keep the day ordinary. Normal naps, normal pottering, no big walk or play session you wouldn't usually do.
- Watch for a low. If a reading is very low, or your pet seems weak or wobbly, stop and treat it as a possible hypoglycemic episode, and call your vet.
Evenly spaced samples across the whole interval matter more than hitting exact clock times. The aim is to catch the lowest point and not miss it in a gap.
Common mistakes that skew results
A curve is easy to run and easy to quietly ruin. The usual culprits:
- Changing the routine "just for the curve." Feeding less, dosing early, or skipping the normal meal makes the curve describe a day your pet never has.
- A stressful sampling process. If getting the drop turns into a wrestling match, the stress itself raises the reading. Keep it calm and brief.
- Milking the sample site hard. Squeezing too much can affect the drop. Use a warm ear and a clean prick instead.
- Gaps at the wrong time. Skipping the middle hours can miss the nadir entirely, which is often the most important point.
- Running a curve on an off day. If your pet is unwell, off their food, or the routine is disrupted, the curve won't mean much. Tell your vet and reschedule.
Presenting the curve to your vet
A curve is only as useful as it is readable. Give your vet a clean list of each time and the reading at that time, plus the times of the meal and the dose, and a note of anything unusual, a low reading, a stressful sample, a refused meal. A simple table or a graph makes the shape obvious at a glance.
Then let your vet do the interpreting. Don't change the dose yourself based on what you see, adjustments come from your vet, weighing the curve against bloodwork, weight, and how your pet is doing day to day. Keeping curves alongside your regular dose and food notes, as in the diabetes care for pets guide, and steady doses in between, as in the missed dose guide, is what makes each curve trustworthy.
Common questions
Does the ear prick hurt my pet?
A quick prick on a warm ear or paw pad is a brief pinch most pets tolerate well, especially with a treat and a calm routine. Warming the ear first and being quick makes it easier. Many cats and dogs settle into it within a few sessions.
My cat's numbers at home look nothing like the vet's. Which is right?
Often both, measuring different days. A stressed cat genuinely does run higher in the clinic, so the home numbers usually reflect ordinary life better. Bring both to your vet rather than deciding which to believe. The comparison itself is useful information, and it's one of the things a fructosamine test helps settle.
How often will my vet want a curve?
More often early on while the dose is being set, then less often once things are stable, with extra curves after any dose change or if something seems off. Your vet sets the schedule, and it's worth asking when the next one should be.
My readings don't match how my pet seems. What do I do?
Note it and tell your vet rather than acting on a confusing number. Meters can vary, a sample can go wrong, and one odd reading isn't the whole story. If your pet seems genuinely unwell, that's a call to your vet regardless of what the meter says.
Where this information comes from
This guide is written from living with a chronically ill dog and checked against published veterinary sources. It's general information, not advice for your individual pet. If you want to read further:
- Feline Diabetes, Cornell Feline Health Center, Cornell University College of Veterinary Medicine. An owner-facing overview of diagnosis, insulin treatment, home monitoring, diet, and remission in cats.
Felova does exactly this, a calm place to record each reading with its time so the curve is readable when your vet needs it. It's on Android now.
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