American Association of Feline Practitioners

Veterinary professionals passionate about the care of cats


Treating diabetic cats is not always straightforward and can be affected by a variety of factors.

Uncontrolled Blood Sugar

  • Review home care, administration, and daily treatment logs
  • Review insulin handling: storage; gentle handling of large, fragile protein structure; and drawing up product correctly (i.e., inversion of vial, ensure not drawing up air)
  • Ensure correct measurement of required dosage: review technique, observe client drawing up insulin
  • Ensure correct syringes being used: U-40 for 40 U/ml and U-100 for 100 U/ml insulins
  • Ensure correct technique for subcutaneous administration: review with client, observe client administering insulin
  • Ensure diet recommendations are being followed


  • Appropriate diagnostic testing for infections should be pursued:
    • Urinalysis
    • Urine culture/sensitivity
    • Note: inactive sediment in urinalysis with dilute urine does not rule out a UTI
  • Appropriate treatment of concurrent infections:
    • Treatment of urinary tract infection based on urine culture and sensitivity testing
    • Treatment of skin infection
    • Treatment of parasites

Dental Disease

  • It may not be possible to achieve diabetic regulation until concurrent dental disease is treated.
  • Management of concurrent dental disease should not be delayed as this may impact insulin responsiveness.
  • Appropriate care for dental disease should be pursued:
    • General anesthesia
    • Dental radiographs
    • Surgical extraction of diseased teeth
    • Scaling and polishing of healthy teeth


Pituitary tumor with excessive production and secretion of growth hormone

  • Effects: Insulin resistant DM secondary to excess growth hormone, anabolic effects of excessive IGF-1, space occupying effect of pituitary macroadenoma
  • Physical changes: weight gain, a broadened face, enlarged feet, protrusion of mandible, increased interdental spacing, organomegaly, poor coat
  • Test: Serum IGF-1 concentration > 1000 ng/mL supports this diagnosis. Note: IGF-1 results may be unreliable in untreated diabetics; testing after 6 weeks of exogenous insulin is recommended. (see side bar References list – Niessen 2007)
  • Cats with hypersomatotropism will require insulin dosages in excessively high ranges (2-70 U daily)


  • Potentially higher risk in tightly controlled patients
  • May be associated with the onset of remission
  • Signs include lethargy, ataxia, dilated pupils
  • Treat with corn syrup, over the counter glucose gels/paste, or sugar water with care to avoid aspiration. Attempt to apply any treatments to the gums
  • Emergency veterinary visit (requires an informed client)
  • Withhold insulin until hyperglycemic again and restart with lowered dose
  • Confirm there has not been overdosing or double dosing

 Somogyi Effect

  • Rebound hyperglycemia as a counter regulatory response to low blood sugar
  • Mediated by effects of adrenaline, cortisol, growth hormone, and glucagon
  • Observed as a BG <70 mg/dL (3.8 mmol/L), followed by a steep rise exceeding 400 mg/dl (22 mmol/L)
  • Documented cases are rare but if suspicions are present, 18 to 24 hour BG curves may be needed to identify

 Switching Insulin

  • No wash out period required
  • Start at the newly diagnosed patient dose (0.25-0.5 U/kg q12h based on lean body weight)
  • Switching insulin should be considered only if duration of effect is an issue or after other troubleshooting has failed to determine a cause for uncontrolled blood sugars

Stress (Excitement) Hyperglycemia

  • A particular issue in feline patients
  • Blood glucose (BG) values of 144-360 mg/dL (8-20 mmol/L) may be falsely elevated due to stress
  • Acute mobilization of glucose
    • BG may exceed the renal threshold (approximately 260 mg/dl [14-16 mmol/L] and result in glucosuria) 

How to differentiate from true DM

  • Urinalysis - there is risk of false positive due to stress glucosuria
  • Home urine testing for glucose or have owner bring in urine sample from home
  • Home BG testing
  • Repeat testing in clinic (with pre-visit sedation, using Feline-Friendly Handling, and pre-visit analgesics where pain may be causing stress)
  • Measurement of serum fructosamine
  • Plasma beta-hydroxybutyrate (>0.22-0.58 mmol/L)

Client Factors to Consider

  • Understanding of treatment, administration/home monitoring, clinical signs, and when to call immediately
  • Compliance and follow-through at home and with routine appointments
  • Daily routine and household factors (travel, work/social schedules, other household pets and humans, stress of client and cat)
  • Multi-cat households where it might be difficult to measure food/water intake and urine output
  • Finances and resources


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© American Association of Feline Practitioners, 2019