Diabetic Cats and Dogs: Tracking Blood Glucose and Insulin

Managing a diabetic cat or dog at home comes down to three things done consistently: insulin at the same times every day with a meal, regular blood glucose readings, and a written log your vet can use to adjust the dose. The AAHA guidelines aim for a lowest reading of about 80 to 150 mg/dL (4.4 to 8.3 mmol/L), with the highest readings close to 200 mg/dL (11.1 mmol/L) in dogs and 300 mg/dL (16.7 mmol/L) in cats. Low blood sugar is the one emergency every owner needs to recognise on sight.

The short answer

• Normal blood glucose in a healthy dog is roughly 70 to 140 mg/dL (3.9 to 7.8 mmol/L); in a healthy cat roughly 70 to 150 mg/dL (3.9 to 8.3 mmol/L). Exact reference ranges vary by laboratory.
• Treatment targets are wider than normal. The goal is a pet without symptoms and without hypoglycemia, not a perfect number.
• Insulin is usually given every 12 hours, with or right after a meal. Your vet sets the type and dose and is the only one who changes it.
• A glucose curve means readings every 2 hours across one dosing interval. It shows how low the glucose goes (the nadir) and how long the insulin lasts.
• Never give insulin to a pet that has not eaten or is vomiting without calling your vet first, and never double up a missed dose.
• Weakness, wobbling, trembling or seizures can mean hypoglycemia. Rub a little honey or corn syrup on the gums and call a vet immediately.

Not sure yet whether your pet has diabetes? Start with the early signs of diabetes in cats and dogs and our symptom checker.

What is a normal blood sugar for cats and dogs?

A diabetic pet on insulin will run higher than a healthy one for much of the day, and that is expected. The table below puts the common figures side by side. They are commonly cited figures, with treatment targets from the AAHA Diabetes Management Guidelines for Dogs and Cats, but reference ranges differ between laboratories and meters, and your vet may set different targets for your pet.

To convert between units, divide mg/dL by 18 to get mmol/L, or multiply mmol/L by 18 to get mg/dL. Always note which unit your meter shows. Mixing them up in a log is a common mistake.

Cats have one extra complication: stress hyperglycemia. A frightened cat at the clinic can show glucose well above 300 mg/dL with no diabetes at all. This is one reason home readings are so valuable for cats. They are often more representative than readings taken in the clinic.

How does a typical insulin schedule for a diabetic cat or dog work?

Most dogs and cats receive insulin twice a day, about 12 hours apart, timed with meals. The routine matters as much as the insulin itself.

A typical day looks like this:

1. Morning: check that your pet is bright and willing to eat. Offer the measured meal.
2. Once your pet has eaten normally, give the prescribed insulin dose, usually within a few minutes to half an hour of the meal, as your vet directs.
3. Record the time, the dose given, how much was eaten and anything unusual.
4. Evening, 12 hours later: repeat the same steps with the second meal.
5. In between: keep treats small and consistent, and avoid big changes in exercise without discussing them with your vet.

A few handling rules apply to almost every insulin:

• Match the syringe to the insulin. Veterinary insulins are often U-40 and human insulins are often U-100. Using the wrong syringe gives the wrong dose. Your vet or pharmacist will tell you which one you need.
• Mix it the way the label says. Some insulins are shaken, others are only gently rolled. Store insulin as instructed, usually in the refrigerator, and check the expiry and discard date.
• Rotate injection sites along the sides of the body so the skin does not thicken in one spot.
• One person gives insulin, or the household uses a shared log, so a dose is never given twice by accident.

Diets are part of the plan too. Many vets recommend a low-carbohydrate, high-protein diet for cats, which the International Society of Feline Medicine (ISFM) consensus guidelines on feline diabetes support, and consistent high-fibre or diabetic diets for many dogs. Some cats that are treated early and well go into diabetic remission and no longer need insulin, which is another reason to monitor at home: a cat heading towards remission can become hypoglycemic on a dose that used to be right. Dogs almost always need insulin for life.

What should you do if your pet will not eat, vomits or you miss a dose?

These are the rules vets teach owners most often. Your own vet may give you slightly different instructions for your pet, and theirs take priority.

1. Not eating or vomiting: do not give the usual insulin dose. Call your vet for instructions. Insulin without food is the classic route to hypoglycemia.
2. Missed dose: do not double the next one. Usually the missed dose is skipped and the normal schedule resumes at the next meal. Ask your vet what they want you to do.
3. Not sure if the dose was given: treat it as given and wait for the next scheduled dose. A slightly high glucose for a few hours is far safer than a double dose.
4. Vomiting, not eating, weakness and a sweet or acetone smell on the breath: these can signal diabetic ketoacidosis, which is an emergency. Go to a vet the same day.

What are the signs of hypoglycemia in cats and dogs, and what should you do?

Hypoglycemia means the blood glucose has dropped too low, usually from too much insulin, a missed meal, vomiting, unusual exercise or a cat moving into remission. It can develop quickly.

Watch for:

• Lethargy, dullness or unusual quietness
• Weakness, wobbling or a drunken walk
• Trembling, twitching or restlessness
• Disorientation, staring or apparent blindness
• Seizures or collapse

What to do, following common veterinary advice:

1. If your pet is alert and can swallow, offer its normal food straight away.
2. If it will not eat or is too weak, rub a small amount of honey or corn syrup onto the gums with your finger. Do not pour liquid into the mouth of a pet that cannot swallow properly, because it can be inhaled.
3. Call your vet or an emergency clinic immediately, even if your pet seems to recover. Hypoglycemia can return.
4. Do not give the next insulin dose until a vet has advised you.
5. If you have a meter, check the glucose and write down the number and the time.

Keep honey or corn syrup somewhere everyone in the household can find it.

How do you do a blood glucose curve at home?

A glucose curve is a series of readings taken over one full dosing interval, typically every 2 hours for 12 hours, as described in the AAHA guidelines. Your vet uses it to see the lowest point, when that point happens and how long the insulin works. Many vets prefer home curves because a relaxed pet at home gives more realistic numbers, especially cats.

What you need:

• A glucose meter your vet recommends. Veterinary-calibrated meters are designed for dog and cat blood; human meters can read differently, so use the same meter every time.
• Lancets, test strips and cotton pads

Steps:

1. Choose the sample site your vet showed you. In cats this is usually the edge of the ear; in dogs the ear, the inside of the lip or a paw pad are common.
2. Take the first reading just before the morning meal and insulin. This is time zero.
3. Feed and inject as usual. Do not change the routine for curve day.
4. Test every 2 hours until the next dose is due. If readings are dropping fast or near the low end, your vet may want hourly checks around the lowest point.
5. Write every reading down immediately with the exact time, plus anything eaten.
6. Send the results to your vet and wait for their decision before changing anything.

Some vets use continuous glucose monitors, small skin sensors that record glucose for up to about two weeks, fitted and interpreted by the vet. Your vet may also run a fructosamine test, which reflects average glucose over roughly the previous one to three weeks, and ask you to check urine for glucose or ketones with test strips. None of these replace watching your pet.

What should a diabetic pet's home log include?

A good log answers the questions your vet will ask. Keep it the same every day:

• Date and time of each meal, and how much was eaten
• Insulin type, the dose given and who gave it
• Glucose readings with the time and the unit
• Water intake and how often your pet urinates, if you can estimate it
• Body weight, weekly on the same scale
• Anything unusual: vomiting, lethargy, a skipped meal, a change in activity

Rising thirst and urination are among the first signs that control is slipping. If you are unsure what counts as normal, our guide to how much water a dog or cat should drink gives figures per kilogram and pound and shows how to measure intake at home. Weight loss matters too; a weekly weigh-in is a simple check, and our cat weight chart gives typical ranges by breed.

How can you log glucose and insulin in PetVitals?

In PetVitals you can add each glucose reading and insulin dose as a health record on your pet's profile, alongside weight and symptoms, and set twice-daily reminders tied to meal times. The glucose chart shows readings over days and weeks, so a curve day or a gradual drift is easy to see. Before an appointment, export a PDF report with the readings, doses and weights to share with your vet. The AI assistant can answer questions using your pet's own records, but it does not change doses and will tell you when something needs a vet.

When should you call the vet?

Call the same day if your diabetic pet:

• Refuses a meal or vomits
• Seems weak, wobbly, confused or has a seizure (treat as hypoglycemia first)
• Is drinking and urinating noticeably more than usual, or losing weight
• Has a glucose reading below the low limit your vet gave you, or repeated very high readings
• Is breathing fast, very lethargic or has a sweet or acetone smell on the breath

For cats, see also signs your cat is sick; many early signs of trouble are subtle.

This article is for general information and does not replace a veterinarian. Insulin type, dose and targets are set by your vet for your individual pet. If you are ever unsure, call your clinic.

Diabetes is a lot to learn at first, but a steady routine and a clear log make it manageable for most families. PetVitals is available for iPhone and Android if you want to keep that log in one place.