Decoding Your Pet’s Glucose Curve: A Simple Guide to What the Numbers Actually Mean

Your pet’s glucose curve shows how glucose changes over time and helps your veterinarian assess the response to insulin.

Instead of focusing on one number, your veterinary team looks at the lowest reading, how long insulin appears to work, and how the pattern fits your pet’s symptoms.

A traditional blood glucose curve uses samples collected at scheduled intervals. Continuous glucose monitoring (CGM) provides a longer record of interstitial glucose patterns, including changes between manual checks.

Understanding these basics can make reports easier to discuss with your veterinarian. Treatment decisions should still follow the care plan established for your dog or cat.

What a Pet Glucose Curve Shows

When your veterinarian reviews a blood glucose curve, they assess how glucose changes throughout an insulin dosing interval.

A conventional curve often involves a reading before feeding and insulin, followed by checks approximately every two hours for 10–12 hours. Your veterinarian may recommend a different schedule depending on the insulin, patient, and reason for testing.

The curve helps answer three questions:

• Nadir: How low does glucose fall?
• Duration: How long does insulin appear to control glucose?
• Overall pattern: Are there repeated highs, lows, or large fluctuations?

The results are interpreted alongside appetite, thirst, urination, body weight, and energy. A curve supports treatment decisions but does not provide the whole picture by itself.

Why One Glucose Reading Isn’t Enough

One glucose reading is a snapshot. Its meaning depends on when it was taken relative to food, insulin, activity, and other events.

Stress can raise glucose, particularly in cats. A reading taken during travel or uncomfortable handling may not reflect the pattern at home.

Likewise, a reassuring reading can miss a low that occurred earlier or a rise before the next dose.

A glucose curve or CGM report provides context by showing changes over time. However, an individual dangerously low reading or concerning symptom still requires prompt attention. Looking at patterns does not mean ignoring an urgent result.

How to Run a Glucose Curve at Home

Before starting a home glucose curve, ask your veterinarian for a written testing schedule and instructions for unexpected results.

Keep your pet’s usual meals, prescribed insulin, and activity routine unless the clinic directs otherwise.

• Use a veterinary-calibrated blood glucose meter and compatible, unexpired strips.
• Ask the veterinary team to demonstrate a suitable sampling site and technique.
• Collect readings at the times requested.
• Record meals, insulin doses, activity, symptoms, and any sampling difficulties.
• Include the units: mg/dL or mmol/L.
• Send the complete record, including unexpected readings.

Do not change the routine to produce a better-looking curve. Your veterinarian needs to understand what happens during everyday care.

If your pet becomes weak, trembles, seems disoriented, collapses, or has a seizure, stop routine testing and seek urgent veterinary advice. Follow the emergency plan rather than waiting to finish the curve.

How Vets Read Nadir and Duration

The nadir and duration describe different parts of insulin response.

A satisfactory lowest reading does not necessarily mean that insulin lasts long enough. Similarly, high readings later in the day do not automatically mean the dose should be increased.

Your veterinarian assesses both features before deciding whether the current treatment is appropriate.

Finding The Nadir

The nadir is the lowest glucose value recorded during the monitoring period.

For many conventional insulin protocols, veterinary guidelines describe a blood glucose nadir of approximately 80–150 mg/dL as a useful reference. Individual goals may differ, especially with basal insulin protocols or other clinical considerations.

The recorded nadir is also limited by the sampling schedule. A manual curve may miss the true lowest point between samples.

Your veterinarian considers:

• Whether the lowest reading is within the individualized goal.
• Whether low values recur or persist.
• Whether symptoms occurred.
• Whether a CGM low needs blood glucose confirmation.
• Whether enough data were collected to identify the lowest point.

Do not use a nadir value to calculate an insulin increase or reduction yourself.

Assessing Insulin Duration

Duration describes how long insulin appears to provide useful glucose control.

For a pet receiving twice-daily insulin, your veterinarian examines whether its effect adequately covers the interval between doses. Other regimens require a different interpretation.

If glucose falls appropriately but rises well before the next dose, the issue may involve duration rather than insufficient dose.

Increasing the dose without understanding that pattern could push the nadir too low. Your veterinarian may instead recommend additional monitoring or a change to the treatment regimen.

Matching Signs To Numbers

The curve should be reviewed alongside what you observe at home.

Useful information includes:

• Increased or reduced thirst.
• Changes in urination.
• Appetite and actual food intake.
• Weight loss or gain.
• Energy and activity.
• Weakness, trembling, or unusual behavior.

Improving symptoms and stable weight can support a favorable assessment. However, the absence of symptoms does not exclude low glucose.

Repeated low readings still need veterinary review, even when your pet appears comfortable.

Glucose Curve Targets for Dogs and Cats

Glucose targets are treatment goals, not universal rules.

Dogs and cats may need different monitoring approaches, and the insulin type can affect how the curve should be interpreted.

Ask your veterinarian to identify the target range and action limits appropriate for your pet.

Ideal Nadir Range

For many conventional insulin-treated dogs and cats, a blood glucose nadir around 80–150 mg/dL is a commonly used reference.

This does not mean every reading throughout the day should fall within that range. It also does not establish a single ideal number, such as 110 mg/dL for every dog or 120 mg/dL for every cat.

Your veterinarian will interpret the nadir alongside duration, symptoms, and the risk of hypoglycemia.

A CGM reading is an interstitial glucose measurement. It should not automatically be treated as interchangeable with a blood glucose result.

Dog Target Range

For diabetic dogs, the aim is to control clinical signs while avoiding hypoglycemia.

Your veterinarian assesses the complete curve rather than requiring every reading to match the normal range of a healthy dog.

A low nadir, a persistently high curve, or insulin that appears to wear off early may each require a different response.

Targets may also differ between conventional and basal insulin protocols. Follow the goals provided for your dog’s prescribed treatment.

Cat Target Range

For insulin-treated cats, glucose patterns should be interpreted with particular attention to stress and changing insulin needs.

A common nadir reference for conventional protocols is also approximately 80–150 mg/dL. A range such as 80–300 mg/dL describes a broader curve assessment, not an acceptable nadir range.

Some cats can enter diabetic remission, which may reduce insulin requirements. Do not stop insulin independently; ask your veterinarian to assess the pattern and establish the next steps.

Cats receiving oral SGLT2 inhibitor medications need a different monitoring plan. Insulin-curve targets should not automatically be applied to them.

When a Glucose Curve Stays Too High

A persistently high glucose curve deserves veterinary review, but it does not automatically prove that more insulin is needed.

Your veterinarian may consider:

• The insulin dose and duration of action.
• Missed or incomplete injections.
• Insulin storage and handling.
• Compatibility of the insulin and dosing equipment.
• Changes in food or activity.
• Stress, particularly in cats.
• Other illnesses that affect glucose control.
• Missing readings or sensor problems.

Do not change insulin dose, timing, or equipment on your own.

High readings accompanied by vomiting, poor appetite, marked lethargy, dehydration, or ketones require prompt veterinary assessment. A glucose curve alone cannot diagnose or exclude diabetic ketoacidosis.

A high reading after a low also needs careful interpretation. Do not assume that every rise represents a glucose bounce or rebound response.

When Low Glucose Becomes an Emergency

Low glucose can be dangerous, especially in a pet receiving insulin.

The urgency depends on the reading, whether glucose is falling, the measurement method, and how your pet is acting. Follow the action limits in your veterinarian’s written plan.

Signs requiring urgent attention include:

• Trembling or weakness.
• Wobbliness or difficulty walking.
• Disorientation or sudden unusual behavior.
• Collapse.
• Seizures.

Contact your veterinarian or an emergency clinic immediately if these signs occur. Check blood glucose if it is safe, but do not delay care to obtain a result.

If your pet is alert and able to swallow, your emergency plan may include offering food. Your veterinarian may also recommend a specific glucose source for application to the gums.

Never force food or liquid into the mouth of a pet that is unconscious, seizing, or unable to swallow.

If a CGM reports a low value while your pet appears normal, follow the instructions for blood glucose confirmation and veterinary contact. Do not dismiss repeated low readings simply because symptoms are absent.

Ask the veterinary team what to do before the next insulin dose. Dose changes should be individualized rather than based on a fixed percentage from an online guide.

How Home Testing Improves Curve Safety

Home testing can provide glucose information within your pet’s familiar environment and usual routine.

This is particularly useful for cats whose glucose may rise during stressful clinic visits. Home monitoring still requires correct technique and a clear response plan.

To improve the usefulness of the results:

• Follow the prescribed testing schedule.
• Use a meter recommended by your veterinarian.
• Keep meals and medication consistent.
• Record symptoms and unusual events.
• Ask for help if sampling becomes difficult.
• Share the complete curve before routine treatment changes.

CGM can add information between manual checks, including overnight patterns and possible lows. It does not eliminate the need for confirmatory blood tests when recommended.

An Adapet CGM system connects sensor monitoring at home with veterinary review through the Vet Portal. Agree with your clinic on when reports will be reviewed and how to contact the team about urgent concerns.

Frequently Asked Questions

How to Interpret Dog Glucose Curve?

Start by identifying the lowest reading, the apparent duration of insulin action, and the overall pattern.

Then compare the results with appetite, thirst, urination, weight, and energy.

Your veterinarian determines whether the pattern suggests adequate control, insufficient duration, excessive insulin effect, or another problem. Do not increase insulin based only on high readings or reduce it using a general online formula.

What Is a Good Chart for a Cat's Glucose Curve?

A useful chart shows time on the horizontal axis and glucose on the vertical axis. It should also identify meal times, insulin administration, and relevant symptoms.

Keep units consistent and distinguish blood glucose measurements from CGM readings.

A clinically useful curve does not need to look smooth or reach one exact number. It needs enough reliable data for your veterinarian to assess the nadir, duration, and safety of treatment.

What Is a Normal Glucose Number for a Dog?

A commonly cited fasting blood glucose range for healthy dogs is approximately 75–120 mg/dL, although laboratory reference intervals vary.

That healthy reference range is different from a treatment target for an insulin-treated diabetic dog.

Do not withhold food or alter insulin to obtain a fasting result unless your veterinarian specifically instructs you to do so.

Use your laboratory’s reference interval and your dog’s individualized monitoring plan when discussing results.

What Do the Numbers Mean on a Glucose Monitor?

A blood glucose meter reports glucose in a blood sample. A CGM reports glucose in interstitial fluid beneath the skin.

The displayed units are usually mg/dL or mmol/L. Confirm which units your device uses before comparing results.

With CGM, trend arrows and the recent curve provide additional context. Sensor glucose can differ from blood glucose, particularly during rapid changes.

Follow your veterinarian’s instructions for unexpected readings, confirmation testing, and urgent symptoms.

Conclusion

Your pet’s glucose curve helps explain how glucose changes throughout treatment.

The nadir, insulin duration, and overall pattern each provide useful information, but they should be interpreted alongside your pet’s symptoms and daily routine.

Keep accurate records, follow individualized targets, and share results with your veterinarian before routine insulin changes. Knowing when to seek urgent help is just as important as understanding the numbers.