American Association of Feline Practitioners

Veterinary professionals passionate about the care of cats


Diabetes mellitus is not always a straightforward diagnosis.  It requires a thorough assessment of clinical signs, individual history, and laboratory results. In the early stages of disease, cats may present with vague signs such as “seems a little off” or “less interactive lately.” Stress hyperglycemia can further complicate or delay diagnosis.

Client Concerns and History

  • Weight loss (or owner's perception that a diet is finally working)
  • Drinking more water
  • Drinking from unusual places
  • Begging for food/insatiable appetite
  • Decreased ability to jump
  • Lethargy
  • Urine is sticky or difficult to clean
  • More frequent urination, larger urine clumps, or urination out of the box

Supportive Clinical Findings

  • Polyuria (PU), Polydipsia (PD), Polyphagia (PP)
  • Weight loss
  • Hyperglycemia and glucosuria; +/- ketonuria         
  • Plantigrade stance
  • DM cats that are weak, depressed, anorexic, vomiting, collapsed, or moribund may have diabetic ketoacidosis (DKA) and require emergency care. (Refer to ISFM Guidelines on Diabetes Mellitus, page 246)


  • Minimum database: CBC, chemistry with electrolytes, Total T4, UA, FeLV/FIV Status
  • Additional tests as appropriate to help confirm diagnosis: Fructosamine and fPL
  • Additional tests as appropriate to fully assess the patient:  blood pressure, UPC ratio, urine culture; also consider cobalamin and folate concentrations, thoracic radiographs, abdominal ultrasound

Complicated Diabetics

The following are comorbidities that may complicate diabetic regulation:

  • Chronic Kidney Disease (CKD)
  • Obesity
  • Urinary Tract Infection (UTI)
  • Dental disease
  • Exposure to human hormone creams
  • Conditions where steroids are a common component of management
  • Acromegaly
  • Hyperadrenocorticism

Diabetes Mellitus Diagnosis

A diagnosis of DM requires documentation of hyperglycemia (BG >250 mg/dl {13.8 mmol/L}) and concurrent glucosuria, plus one or more of the following pieces of supportive evidence:

  • A history of PU/PD/PP and ketonuria
  • An increased serum fructosamine concentration
  • An increased glycated hemoglobin % (HgA1c)
  • Documentation of hyperglycemia in the home environment (BG >250 mg/dl) 24 hours after a hospital visit
  • Documentation of glucosuria in the home environment 24 hours after a hospital visit

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© American Association of Feline Practitioners, 2019