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Diagnostics2026-05-25 · 12 min read

Feline Diabetes Monitoring: Glucose Curves, Fructosamine, CGMs

The 2026 AAHA Diabetes Management Guidelines for cats no longer recommend routine in-hospital blood glucose curves.

Ran Chen
Ran Chen
Founder, VetMedGuide. Life-sciences operator and 10× global market-access lead.
Published

On April 26, 2026, the American Animal Hospital Association (AAHA) published its first diabetes management guidelines written specifically for cats. The document builds on the 2018 AAHA Diabetes Management Guidelines for Dogs and Cats but reflects how dramatically feline diabetes treatment has diverged from canine management — driven partly by two new SGLT2-inhibitor drugs (Bexacat, approved 2022; Senvelgo, approved 2023) and partly by growing evidence that cats are poorly served by monitoring tools designed for dogs and humans.

The single most attention-getting recommendation: routine in-hospital blood glucose curves (BGCs) are no longer recommended for diabetic monitoring in cats. The reason is stress hyperglycemia. Hospitalized cats frequently produce glucose readings that are artificially elevated by the stress of hospitalization itself, making in-hospital curves unreliable for guiding insulin dose adjustments.

This article explains what the 2026 guidelines recommend instead, compares each monitoring tool — continuous glucose monitors (CGMs), fructosamine testing, at-home blood glucose curves, clinical sign tracking, and urine monitoring — and helps veterinary teams and cat owners understand which tool fits which situation.

Why feline diabetes monitoring is different

Diabetes mellitus in cats shares pathophysiologic features with human type 2 diabetes: insulin resistance, beta-cell dysfunction, and obesity as a risk factor. But cats have a characteristic that makes glucose monitoring uniquely difficult: stress hyperglycemia.

A cat that is calm at home can produce a blood glucose reading 50–100 mg/dL (or more) higher in the veterinary hospital simply from the stress of transport, handling, and the clinic environment. A 2023 review in Veterinary Clinics of North America: Small Animal Practice confirmed that stress-related hyperglycemia is a well-documented phenomenon in feline patients and can significantly confound glucose curve interpretation.

This is the central reason the 2026 AAHA guidelines moved away from in-hospital curves. A curve that shows persistently high glucose may reflect the cat's stress response, not its actual diabetic control. Adjusting insulin based on those numbers risks overcorrection and hypoglycemia.

Cats also differ from dogs in that diabetic remission is possible. With aggressive glycemic control — particularly using insulin glargine or detemir in newly diagnosed cats — some cats can achieve normoglycemia without ongoing medication. This makes accurate monitoring even more important, because the goal is not just control but potential remission, and the monitoring strategy needs to detect remission, impending hypoglycemia, and the need for dose reduction.

The 2026 AAHA monitoring recommendations

The guidelines recommend that feline diabetic monitoring be based on a combination of tools rather than any single test:

  1. Clinical signs — water intake, urine output, appetite, weight, and activity level
  2. Continuous glucose monitoring (CGM) — primarily the FreeStyle Libre system
  3. At-home blood glucose data — using a veterinary-calibrated portable blood glucose meter (PBGM) such as AlphaTRAK 2 or an owner-performed home glucose curve
  4. Fructosamine trends — a single blood test reflecting average blood glucose over the previous 1–3 weeks
  5. Caregiver observations — the owner's day-to-day assessment of the cat's condition

In-hospital blood glucose curves are explicitly not recommended as a routine monitoring tool. They may still have a role in specific situations — for example, when a cat is hospitalized for diabetic ketoacidosis (DKA) and CGM or home testing is not available — but they are no longer the default.

Continuous glucose monitoring (CGM)

The FreeStyle Libre (FSL) is the CGM system most commonly used in veterinary medicine. It reports an average interstitial glucose concentration every 15 minutes for up to 14 days (the human label says 14; in practice, veterinary teams sometimes get slightly shorter wear times in cats due to sensor adhesion).

What the 2026 AAHA guidelines say about CGM

The guidelines describe CGM as a tool that "provides continuous glycemic data without the need for serial blood draws" and note that successful use in cats has been reported in multiple studies. The guidelines also caution that:

  • CGM is not calibrated for veterinary patients, and results may differ from veterinary-calibrated PBGMs (like AlphaTRAK).
  • The FSL can be less accurate at low glucose readings, and any low reading should be confirmed with a PBGM before making treatment decisions, especially if the cat is not showing clinical signs of hypoglycemia.
  • Clients with real-time access to CGM data can become overly focused on individual readings and may attempt to adjust therapy independently. Setting expectations during client education is important.

Practical considerations for CGM in cats

  • Placement: The sensor is typically placed on the dorsal neck, lateral thorax, or flank. The area is clipped and cleaned before application. Most cats tolerate the sensor well after a brief adjustment period.
  • Duration: Each sensor lasts up to 14 days. In a stable diabetic cat, a 14-day CGM trace every few months may provide more actionable data than a single in-hospital curve.
  • Cost: Sensors cost approximately $50–75 each (over-the-counter pricing). This compares favorably to the cost of an all-day hospital stay for a glucose curve, particularly when the hospital curve may be unreliable.
  • Limitations: Sensor detachment, skin reactions, and discrepancies at low glucose values are the main practical issues. Having a PBGM for confirmation remains important.

The 2026 AAHA resource center includes video training on FSL placement and report interpretation, developed by Purdue University.

Fructosamine testing

Fructosamine is a glycated serum protein that reflects the average blood glucose concentration over the previous 1–3 weeks. Unlike a spot blood glucose reading or a glucose curve, fructosamine is not affected by stress hyperglycemia, because it represents a time-averaged value rather than a single point-in-time measurement.

What fructosamine tells you

  • A fructosamine concentration within or close to the reference range (roughly 146–271 µmol/L in cats, though lab-specific ranges vary) suggests adequate glycemic control over the preceding weeks.
  • A fructosamine concentration above 400 µmol/L generally indicates poor glycemic control, as documented in a pivotal study published in the Journal of Veterinary Internal Medicine.
  • Fructosamine does not detect rapid glucose fluctuations. A cat with wide daily swings from hyperglycemia to hypoglycemia could have a deceptively normal fructosamine. For this reason, fructosamine is best used alongside clinical sign assessment, not as the sole monitoring tool.

When to use fructosamine

  • As a screening tool when a diabetic cat is due for a recheck but CGM or home testing is not available.
  • To confirm or refute a concerning glucose curve when stress hyperglycemia is suspected.
  • For long-term monitoring of a stable diabetic cat — every 3–6 months, depending on the cat's status.
  • In cats where home glucose monitoring or CGM is not feasible — for example, cats whose owners cannot perform home testing and cats that will not tolerate a sensor.

Fructosamine requires a blood draw by a veterinary professional. It cannot be performed at home.

At-home blood glucose curves

Before CGMs became widely available, the at-home blood glucose curve (BGC) was the primary alternative to in-hospital curves. The technique involves the cat owner obtaining serial blood glucose readings at home using a veterinary-calibrated portable blood glucose meter (PBGM).

How it works

The owner pricks the cat's ear margin or paw pad with a lancet, applies a small blood drop to a test strip, and records the glucose value. A full curve typically involves readings every 2 hours over a 12-hour period, centered around the insulin injection.

Advantages and limitations

  • Advantage: Eliminates the stress hyperglycemia that makes in-hospital curves unreliable. Readings reflect the cat's actual glucose level in its home environment.
  • Limitation: Not all owners can perform this. Practical problems include difficulty obtaining a sufficient blood sample, the cat's resistance to repeated sampling, and the time commitment required.
  • Limitation: Even at home, cats can experience some stress-related glucose elevation during the sampling process itself, though it is generally much less than in the hospital.

The 2026 AAHA guidelines note that at-home BGCs "continue to be a helpful option in some cats" but acknowledge that not all clients are suited to the task.

Clinical sign monitoring

Regardless of which laboratory or device-based monitoring tool is used, clinical signs remain the most accessible and arguably the most important indicator of diabetic control. The 2026 AAHA guidelines emphasize that clinical assessment should always accompany — not be replaced by — numerical glucose data.

Signs of good diabetic control

  • Stable or gradually decreasing body weight (or weight gain in a cat that was underweight at diagnosis)
  • Normal water intake (no excessive thirst/polydipsia)
  • Normal urine output (no polyuria)
  • Good appetite without excessive hunger (polyphagia)
  • Normal activity level
  • No recurrence of diabetic neuropathy (plantigrade stance)

Signs of poor control

  • Persistent polydipsia and polyuria
  • Weight loss despite a good appetite
  • Persistent or recurrent diabetic neuropathy
  • Poor coat condition
  • Recurrent urinary tract infections

Signs of potential hypoglycemia (emergency)

  • Lethargy, weakness, or collapse
  • Disorientation or ataxia
  • Seizures
  • These signs require immediate veterinary attention.

Owners should understand that the goal of treatment is to resolve clinical signs, not to achieve a specific glucose number. A cat that is drinking normally, maintaining weight, and acting like itself is likely well-controlled, even if individual glucose readings fluctuate.

Monitoring cats on SGLT2 inhibitors

The 2026 AAHA guidelines dedicate significant attention to monitoring cats receiving SGLT2 inhibitors (Bexacat or Senvelgo), because these drugs carry specific risks that differ from insulin therapy.

SGLT2 inhibitors work by blocking glucose reabsorption in the kidneys, causing glucose to be excreted in urine. This lowers blood glucose without insulin. However, they are only appropriate for cats that meet specific criteria — they must be otherwise healthy, not have concurrent conditions like CKD or hepatic disease, and not have been previously treated with insulin. Both Bexacat (bexagliflozin tablets) and Senvelgo (velagliflozin oral solution) carry this restriction on their labels; using either drug in a cat with prior insulin exposure increases the risk of diabetic ketoacidosis and death.

The critical monitoring concern with SGLT2 inhibitors is diabetic ketoacidosis (DKA). The guidelines emphasize that any cat on an SGLT2 inhibitor that shows lethargy, anorexia, vomiting, or dehydration should be evaluated urgently for DKA, regardless of glucose readings. DKA can occur with normal or near-normal blood glucose in cats on SGLT2 inhibitors (euglycemic DKA).

Monitoring for cats on SGLT2 inhibitors includes:

  • Clinical signs at every check-in
  • Fructosamine to assess overall glycemic control
  • Urine ketone monitoring at home using urine test strips
  • Blood work including electrolytes and kidney values at regular intervals

Putting it together: a monitoring framework

The optimal monitoring strategy depends on the treatment, the cat's stability, and the owner's capabilities. The following table summarizes how the tools fit together:

Situation Primary tool Supporting tools Frequency
Newly diagnosed cat starting insulin CGM (if available) or at-home BGC Clinical signs, fructosamine CGM or BGC at 1–2 weeks after starting; fructosamine at 2–4 weeks
Stable diabetic on insulin Clinical signs + fructosamine CGM or BGC if signs change Fructosamine every 3–6 months; clinical signs ongoing
Cat approaching remission CGM or at-home BGC Fructosamine, clinical signs More frequent monitoring as insulin is tapered
Cat on SGLT2 inhibitor Clinical signs + fructosamine + urine ketones CGM if available Per label recommendations; urgent evaluation for any sign of DKA
Cat where home testing/CGM not feasible Fructosamine + clinical signs Periodic in-hospital glucose spot checks (not full curves) Every 2–4 weeks until stable, then every 3–6 months

What cat owners should ask their veterinarian

The shift away from in-hospital curves is recent enough that some practices may still default to them. Cat owners managing a diabetic cat should feel empowered to discuss the monitoring plan with their veterinarian:

  • "What monitoring method do you recommend for my cat?" The answer should account for the cat's temperament, the treatment being used, and the owner's ability to participate in home monitoring.
  • "Should we consider a continuous glucose monitor?" CGMs are increasingly available and may reduce the need for stressful hospital visits, but they are not the right tool for every cat or every owner.
  • "How often should fructosamine be checked?" For most stable diabetic cats, every 3–6 months is reasonable. More frequent checks may be needed during dose adjustments or treatment changes.
  • "What clinical signs should I track at home?" Water intake, urine output, appetite, weight, and activity level are the core parameters. Keeping a simple log makes veterinary visits more productive.
  • "What do I do if I see signs of hypoglycemia or DKA?" Both are emergencies. Owners should have a clear plan for after-hours contact and emergency transport before these situations arise.

Sources

Topics
EndocrinologyFeline CKDClinical Pathology
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