Section 3: Diagnosing DM in Cats

Recommended Laboratory Tests for Cats with Clinical DM Signs:

• Complete blood count (CBC)
• Chemistry panel with cholesterol, triglycerides, and electrolytes
• Urinalysis with sediment examination
• Serum total thyroxine (TT4) concentration

Confirming a diagnosis of DM in cats exhibiting clinical signs requires proof of sustained hyperglycemia using one or more of the following methods:

• Evidence of increased glycated protein concentrations, such as increased fructosamine.¹ Protein glycation is the nonenzymatic, insulin-independent, irreversible binding of glucose to the parent molecule, and glycation rates are therefore influenced by BG concentrations. Fructosamines are a group of glycated plasma proteins, including albumin, with a relatively short half-life. Fructosamine measurement therefore reflects average BG over the previous 7–10 days.² This value tends to be higher in male cats than females³ and may be lowered by conditions that shorten the half-life of albumin, such as hyperthyroidism and protein-losing diseases.^4,5
• Glycated hemoglobin (HbA1C; expressed as a percent) is widely used for diabetes diagnosis and monitoring in people, and it reliably reflects average BG in cats over the previous 2–3 mo.⁶ Although a commercial test is available to veterinarians, the task force is not aware of any feline HBA1C assays that have been validated in diabetic cats.⁷ More studies are needed to assess their clinical use in cats.
• Alternatively, a CGM placed on the patient, a portable blood glucose monitor (PBGM), or glucosuria detection products can assess whether persistent hyperglycemia or glucosuria occurs when cats are at home. CGMs record the interstitial glucose concentration continuously over multiple days. See Section 13, Glucose Monitoring, for more information.
• Concurrent ketosis—diagnosed by a finding of ketonuria or blood beta-hydroxybutyrate (BHB) concentration >1.0 mmol/L (see Box) in a patient meeting DM diagnostic criteria—suggests a more complicated or advanced stage of disease (see Section 12, Diabetic Ketoacidosis).
• If clients are unable to pursue fructosamine testing and/or use a CGM or PBGM, they can try to collect urine samples at home to check for glucosuria. It is ideal for clients to wait at least 2-3 days after an in-hospital examination or stressful event to begin collecting urine and aim to obtain at least 2 urine samples voided on different days to document persistence.⁸ If that is not possible, clinicians can consider instituting therapy if clinical suspicion for DM is high, or recheck the cat’s weight and laboratory evaluation within 1-2 weeks.

Blood Beta-Hydroxybutyrate

BHB is the earliest and most predominant ketone body produced during diabetic ketoacidosis in cats. Point-of-care whole blood ketone analyzers (ketone meters) are available to measure BHB, and a commercial model has been validated in cats.^a

^a. Weingart C, Lotz F, Kohn B. Validation of a portable handheld whole-blood ketone meter for use in cats. Vet Clin Pathol 2012;41(1):114–8.

The 2026 AAHA Diabetes Management Guidelines for Cats are generously supported by Adapet Medical, Boehringer Ingelheim, Dechra, and Merck Animal Health.