Contributors: David Bruyette, Carmel Mooney, Nicki Reed

 Species: Feline   |   Classification: Diseases

Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading


  • Common endocrine disease of middle-aged cat (approx. 1 in 400).
  • Cause: syndrome characterized by relative or absolute lack of insulin.
  • Signs: polyuria/polydipsia.
  • Diagnosis: glycosuria, persistent hyperglycemia, fructosamine.
  • Treatment: insulin, dietary management.
  • Prognosis: generally good if uncomplicated by concurrent condition.
    Print off the owner factsheets on Diabetes mellitus Diabetes mellitus and Monitoring diabetes in cats Monitoring diabetes in cats to give to your client.

Presenting Signs

  • Uncomplicated:
    • Polydipsia/polyuria.
  • Weight loss.
  • Anorexia (particularly if ketotic).
  • Lethargy.
  • Gait abnormalities (plantigrade stance).

Acute Presentation

  • Signs of diabetic ketoacidosis Diabetic ketoacidosis (anorexia, vomiting, dehydration, coma, death).
  • Hyperosmolar non-ketotic diabetes has been reported in the cat but appears to be rare.

Age Predisposition

  • Middle-aged to old - mean 11 y (range 7-14 years).
  • Rarely juvenile.

Breed Predisposition

  • Burmese Burmese reported to be over-represented in Australia, New Zealand and UK.
  • Maine Coon Maine Coon, Domestic longhair, Russian Blue Russian Blue, and Siamese Siamese  possibly over-represented in USA.

Special Risks

  • Anesthesia Anesthesia: in diabetic patient requires careful planning.
  • Usually administer half dose of insulin prior to surgery and administer glucose in fluids during procedure.
  • Aim to get animal eating and back on usual regime as soon as possible after surgery.
    Warn owner of risks associated with anesthesia.



  • Type 1: inadequate secretion of insulin (immune-mediated, destruction of islet cells).
  • Type 2: resistance to insulin activity, eg obesity Obesity leading to relative lack of insulin (most common).
  • Type 3: antagonism to insulin (cortisol, progesterone, growth hormone, catecholamines, glucagon).
  • Inactivation of insulin (immune response).

Predisposing Factors


  • Increasing age (may be due to increased presence of diseases causing insulin resistance in older cats).
  • Obesity:
    • Associated with indoor lifestyle.
  • Concurrent disease:
  • Drug therapy:
    • Progestagen therapy, eg megestrol acetate.
    • Glucocorticoids.
    • Cyclosporin may alter glucose homeostasis in humans and dogs (not documented in cats).
  • Genetic susceptibility.


  • Type 1: (insulin dependent - rare) destruction of beta cells (immune-mediated/congenital/neoplastic    →   failure of insulin response to hyperglycemia.
  • Type 2: (non-insulin dependent - most common) peripheral insulin resistance   →   increased insulin production required   →    glucose toxicity and increased amylin secretion    →   fall in insulin levels and islet amyloidosis    →   beta cell degeneration   →    type 1 diabetes.
  • Type 3: (concurrent disease - 5-10%) endocrinopathies or insulin antagonistic drugs   →   increased requirement for insulin   →   initial hyperinsulinemia   →   beta cell degeneration   →   type 1 diabetes.


  • Weeks to months.


Presenting Problems

  • Polydipsia/polyuria.

Client History

  • Developing over a few weeks:
    • Polydipsia/polyuria.
    • Gait abnormalities.
  • Anorexia.
  • Vomiting.
  • Polyphagia.
  • Weakness.

Clinical Signs

  • Depression.
  • Abnormal weight (obesity  Obese cat 01  Obese cat 02 or thin).
  • Muscle wastage.
  • Hepatomegaly Hepatomegaly.
  • Unkempt hair coat.
  • Dehydration.
  • Bacterial infections (urinary tract, respiratory tract).
  • Icterus.
  • Thickened intestinal loops.
  • Plantigrade stance (peripheral neuropathy)  Neuropathy: diabetic .

Diagnostic Investigation





  • Stress leukogram may or may not be present, as hyperglycemia may reduce mobilization of neutrophils.
  • PCV Hematology: packed cell volume may be increased due to hemoconcentration in dehydrated patients.
  • PCV may be reduced due to Heinz body anemia (particularly if ketotic).

2D Ultrasonography

Gross Autopsy Findings

  • Hepatomegaly.

Histopathology Findings

  • Pancreatic amyloidosis.

Differential Diagnosis

Many cats with diabetes mellitus have concurrent disease.


Initial Symptomatic Treatment

  • If cat is depressed or anorexic fluid therapy and nutritional support may be required.
  • The aim of treatment is to address the underlying cause:
    • Primary disease treat with insulin.
    • Secondary disease treat underlying condition (although may need insulin support in interim).

Standard Treatment

Aims of treatment

  • Resolve clinical signs.
  • Avoid hypoglycemia Hypoglycemia.
  • Achieve diabetic remission.

Dietary control

  • High protein/low carbohydrate diets, with <15% of energy requirements from carbohydrates, should be fed unless concurrent chronic kidney disease, as increased rates of remission have been demonstrated.
  • High fiber, moderate protein diets may be used as an alternative.
  • Wet foods appear to be better than dry foods at controlling weight.
  • Meal feeding in association with insulin injections is not necessary:
    • There is not such a marked post-prandial hyperglycemic peak in cats.
    • Ad lib 'grazing' is more consistent with their natural feeding pattern.
  • If the patient is obese reduce caloric level to 75% of cat's ideal weight.
  • In non-obese patients normal maintenance rations should be fed.

Oral hypoglycemic agents

  • Best reserved for normal or obese, non-ketotic cats with no underlying disease and only mild increases in blood glucose.
  • See component oral hypoglycemics for further details Oral hypoglycemic agents but most commonly used is glipazide:
    • Stimulates beta cells to produce more insulin.
    • May be less likely to induce recovery from glucose toxicity.

Insulin therapy

  • Different insulins available - few have veterinary licences:
    • Bovine insulin is very similar to feline insulin (differing by a single amino acid):
      • Bovine Protamine zinc insulin Insulin is considered to be long-acting.
      • Once or twice daily by subcutaneous injection (Blue Ridge Pharmaceuticals).
    • Porcine lente insulin:
      • Must be given twice daily, sometimes 3-4 times daily.
      • 40 iu/ml formulation is useful for small doses required in cats.
    • Glargine Insulin glargine and detemir Insulin detemir:
      • Human recombinant insulins.
      • Considered to be 'peakless' therefore risk of hypoglycemia reduced.
      • Best given twice daily.
  • See standard stabilization routine Diabetes: management regimens
    If animal is ketoacidotic always use insulin therapy, not oral hypoglycemics alone.

Agents for use in combination with insulin

  • Thiazolidinediones, eg troglitazone (Resulin) 20-40 mg/kg SID increase insulin-dependent glucose disposal, but there are no studies on efficacy in diabetic cats.
  • Transition metal compounds, eg vanadium Vanadium and chromium Chromium have recently been used clinically to lower blood glucose levels in non-insulin dependent diabetic cats, although latest data has shown little benefit.
  • Some agents, eg alpha-glucosidase inhibitors (acarbose) impair glucose absorption from the intestine, but are more effective in 'meal-fed' cats.


Laboratory monitoring

  • Blood glucose curves performed:
    • 7-10 days into treatment to allow for decrease in glucose toxicity.
    • 7-10 days after adjustment in management.
    • If there is a question over stability.
  • Monitor serum fructosamine Blood biochemistry: fructosamine or glycosylated hemoglobin Glycosylated hemoglobin to determine long-term stability - particularly for stressed or fractious cats.
  • Renal function by urea, creatinine and urine SG measurements.
  • If oral hypoglycemics are used periodic hemograms and biochemistry to monitor for side-effects (increased hepatic enzymes, possible blood dyscrasias, hypoglycemia).

Home monitoring by owner

  • Monitor for hypoglycemia:
    • Owners should be made aware of potential signs of hypoglycemia, namely weakness/wobbliness, tremors, twitching or seizures, dilated pupils, unusual fear or hiding behaviors.
  • Resolution of clinical signs (best guide to stabilization).
  • Water intake at home (usually <60 ml/kg/day on dry food or <20 ml/kg/day on wet food) indicates glycemic control is good.
  • Weight - diet should be adjusted accordingly (if losing weight increase caloric intake; if gaining reduce caloric intake.
  • Urine glucose 2-3 times weekly:
    • If on PZI or Lente insulin:
      • Repeated negative urine glucose may indicate remission. Check blood glucose.
      • Do not use positive values to increase insulin dose.
    • If on glargine/detemir:
      • Negative gluosuria may be less likely to indicate remission, as blood lgucose exceeds renal threshold less frequently.
      • Persistent glucosuria may indicate need to increase dose.
  • Development of complications associated with disease:
    • Diabetic neuropathy (plantigrade stance) may arise with poor glycemia control.
    • Cataracts rarely cause clinical complications in cats. 
  • Purina Glucotest" is a litter additive that supposedly can be used to accurately assess glucosuria. Results suggest that the Glucotest" tends to overestimate urine glucose concentrations in the midranges (50-300 mg/dL), even when exposed to urine glucose conentrations that directly correlate with the published color chart. The 8 hr measurements were more accurate than the initial readings but the change over time is not consistent with the labeled 8-hr color stability claim.
  • Home blood glucose curves may be performed by committed owners. Reduce stress and inappetence that may be associated with hospital generated curves and therefore more likely to reflect true control.
  • If there is a discrepancy between owner reporting stability and laboratory tests indicating poor control then owner is more likely to be correct and laboratory effects may be due to stress hyperglycemia.

Subsequent Management


  • Development of hypoglycemia should be treated with:
    • Glucose solutions applied to gums by owner (honey can be used in an emergency).
    • Glucose may be instilled into rectum if concern re getting bitten.
    • Intravenous administration of 10% glucose (0.2-0.4 ml/kg) over 10 mins, followed by constant rate infusion of 2.5-5% glucose as required.
    • Glucagon injection can be considered for insulin overdose given as a constant rate infusion.



  • Mean survival times 1-2 years.
  • Prognosis may be better in cats that achieve remission, which usually occurs within 4 months of initiating therapy. 
  • Remission rates reported to be:
    • 80-90% for glargine with intensive monitoring.
    • 40% for protamine zinc insulin.
    • 30% for porcine lente insulin.
  • Approximately 25-40% may relapse again after achieving remission. 
  • Mortality rate in first year after diagnosis is high but if a case survives this period long term prognosis is better.
  • Presence of concurrent disease may worsen prognosis.

Expected Response to Treatment

  • Resolution of clinical signs.
  • In some cases disease may resolve completely.

Reasons for Treatment Failure

  • Concurrent disease Diabetes mellitus: pathophysiology. Investigate for and treat where feasible:
    • Urinary tract infection.
    • Pancreatitis/pancreatic neoplasia.
    • Acromegaly.
    • Hyperthyroidism.
    • Dental disease.
    • (Hyperadrenocorticism - rare.)
  • Owner non-compliance with treatment:
    • Check insulin storage and administration.
    • Inappropriate diet.
  • Inappropriate treatment regime:
    • Adjusting insulin dose based on urine glucose.
    • Only giving insulin once daily.
    • Not rotating injection site.
  • Side effects or complications associated with treatment:
    • Hypoglycemic episodes.
    • Somogyi overswing.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Roomp K, Rand J S (2012) Evaluation of detemir in diabetic cats managed with a protocol for intensive glucose control. J Feline Med Surg 14 (8), 566-572 PubMed.
  • Scott-Moncreiff J C (2012) Insulin resistance in cats. Vet Clin N America Small Anim Pract 40 (2), 241-257 PubMed.
  • Marshall R D, Rand J S & Morton J (2009) Treatment of newly diagnosed diabetic cats with glargine insulin imporves glycemia control and results in higher probability of remission than protamine zinc and lente insulins. J Feline Med Surg 11 (8), 683-691 PubMed.
  • Roomp K, Rand J S (2009) Intensive blood glucose control is safe and effective in diabetic cats using home monitoring and treatment with glargine. J Feline Med Surg 11 (8), 668-682 PubMed.
  • Marshall R, Rand J, Morton J (2008) Insulin glargine has a long duration of effect following administration either once daily or twice daily in divided doses in healthy cats. J Feline Med Surg 10 (5), 488-494 PubMed.
  • Marshall R, Rand J, Morton J (2008) Glargine and protamine zinc insulin have a longer duration of action and result in lower mean daily glucose concentrations than lente insulin in healthy cats. J Vet Pharmacol Ther 31 (3), 205-212 PubMed.
  • Bennett N, Greco D S, Peterson M E et al (2006) Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus. J Feline Med Surg (2), 73-84 PubMed.
  • Reusch C E, Tschour F, Kley S et al (2006) Diabetes mellitus in the cat: a review. Schweiz Arch Tierheilkd 148 (3), 130-138 PubMed.
  • Weaver K E, Rozanski E A, Mahony O M et al (2006) Use of glargine and lente insulins in cats with diabetes mellitus. J Vet Intern Med 20 (2), 234-8 PubMed.
  • Casella M, Hässig M & Reusch C E (2005) Home-monitoring of blood glucose in cats with diabetes mellitus: evaluation over a 4-month period. J Feline Med Surg (3), 163-171 PubMed.
  • Rand J S & Marshall R D (2005) Diabetes mellitus in cats. Vet Clin North Am Small Anim Pract 35 (1), 211-224 PubMed.
  • Ristic J M, Herrtage M E, Walti-Lauger S M et al (2005) Evaluation of a continuous glucose monitoring system in cats with diabetes mellitus. J Feline Med Surg (3), 153-162 PubMed.
  • Van de Maele I, Rogier N & Daminet S (2005) Retrospective study of owners' perception on home monitoriong of blood glucose in diabetic dogs and cats. Can Vet J 46 (8), 718-723 PubMed.
  • Kley S, Casella M & Reusch C E (2004) Evaluation of long-term home monitoring of blood glucose concentrations in cats with diabetes mellitus: 26 cases (1999-2002)JAVMA 225 (2), 261-266 PubMed.
  • Nelson R, Spann D, Elliott D et al (2004) Evaluation of the oral antihyperglycemic drug metformin in normal and diabetic cats. J Vet Intern Med 18 (1), 18-24 PubMed.
  • Rand J S, Fleeman L M, Farrow H A et al (2004) Canine and feline diabetes mellitus: nature or nuture? J Nutr 134 (8 Suppl), 2072S-2080S PubMed.
  • Thiess S, Becskei C, Tomsa K et al (2004) Effects of high carbohydrate and high fat diet on plasma metabolite levels and on i.v. glucose tolerance test in intact and neutered male cats. J Feline Med Surg (4), 207-218 PubMed.
  • Mazzaferro E M, Greco D S, Turner A S et al (2003) Treatment of feline diabetes mellitus using an alpha-glucosidase inhibitor and a low-carbohydrate diet. J Feline Med Surg (3), 183-189 PubMed.
  • Sennello K A, Schulman R L, Prosek R et al (2003) Systolic blood pressure in cats with diabetes mellitus. JAVMA 223 (2), 198-201 PubMed.
  • Wiedmeyer C E, Johnson P J, Cohn L A et al (2003) Evaluation of a continuous glucose monitoring system for use in dogs, cats, and horses. JAVMA 223 (7), 987-992 PubMed.
  • Bennett N (2002) Monitoring techniques for diabetes mellitus in the dog and the cat. Clin Tech Small Anim Pract 17 (2), 65-69 PubMed.
  • Zoran D L (2002) The carnivore connection to nutrition in cats. JAVMA 221 (11), 1559-1567 PubMed.
  • Zerbé C A (2001) What is so special about feline diabetes mellitus? J Feline Med Surg (2), 99-103 PubMed.
  • Behrend E N & Greco D S (2000) Feline diabetes mellitus - evaluation of treatment. Comp Cont Ed Pract Vet 22 (5), 440-453 VetMedResource.
  • Elliott D A, Feldman E C, Koblik P D et al (2000) Prevalence of pituitary tumours among diabetic cats with insulin resistance. JAVMA 216 (11), 1765-1768 PubMed.
  • Hoenig M, Hall G, Ferguson D et al (2000) A feline model of experimentally induced islet amyloidosis. Am J Pathol 157 (6), 2143-2150 PubMed.
  • Hoenig M, Reusch C & Peterson M E (2000) Beta cell and insulin antibodies in treated and untreated diabetic cats. Vet Immunol Immunopathol 77 (1-2), 93-102 PubMed.
  • Nelson R W (2000) Oral medications for treating diabetes mellitus in dogs and cats. JSAP 41 (11), 486-490 PubMed.
  • Nelson R W (2000) Selected topics in the management of diabetes mellitus in cats. Journal Fel Med Surg (2), 101-104 PubMed.
  • Norman E J & Mooney C T (2000) Diagnosis and management of diabetes mellitus in five cats with somatotrophic abnormalities. JFMS (4), 183-190 PubMed.
  • Feldhahn J R, Rand J S, Kinnaird E (1999) The effect of interday variation and a short term stressor on insulin sensitivity in clinically normal cats. J Fel Med Surg 1 (4), 233-240 PubMed.
  • Foldhahn J R & Martin G (1999) Insulin sensitivity in normal and diabetic cats. J Feline Med Surg (2), 107-15 PubMed.
  • Godfrey D R (1999) What is your diagnosis? Non-ketotic hyperosmolar diabetes mellitus. JSAP 40 (9), 409, 450 PubMed.
  • Greco D S (1999) Insulin therapy in cats. JAAHA 35 (4), 269-270 PubMed.
  • Martin G J W, Rand J S (1999) Food intake and blood glucose in normal and diabetic cats fed ad libitum. J Fel Med Surg (4), 241-251 PubMed.
  • Nelson R W, Griffey S M, Feldman E C et al (1999) Transient clinical diabetes mellitus in cats - 10 cases (1989-1991). J Vet Intern Med 13 (1), 28-35 PubMed.
  • Rand J (1999) Current understanding of feline diabetes. Part 1, Pathogenesis. J Feline Med Surg (3), 143-53 PubMed.
  • Feldman E C, Nelson R W & Feldman M S (1997) Intensive 50-week evaluation of glipizide administration in 50 cats with previously untreated diabetes mellitus. JAVMA 210 (6), 772-777 PubMed.
  • Kraus M S, Calvert C A, Jacobs G J et al (1997) Feline diabetes mellitus a retrospective mortality study of 55 cats (1982-1994). JAAHA 33 (2), 107-111 PubMed.
  • Rand J S, Bobbermien L M, Hendrikz J K et al (1997) Over-representation of Burmese cats with diabetes mellitus in Australia. Aust Vet J 75 (6), 402-405 PubMed.
  • Crenshaw K L & Peterson M E (1996) Pre-treatment clinical and laboratory evaluation of cats with diabetes mellitus 104 cases (1992-1994). JAVMA 209 (5), 943-949 PubMed.
  • Crenshaw K L, Peterson M E, Heeb L A et al (1996) Serum fructosamine concentrations as an index of glycemia in cats with diabetes mellitus and stress hyperglycemia. JVIM 10 (6), 360-364 PubMed.
  • Carlson R A (1994) Hyperosmolar nonketotic diabetes mellitus in a cat. Feline Pract 22 (3), 20-24 VetMedResource.
  • Kirk C A, Feldman E C & Nelson R W (1993) Diagnosis of naturally acquired Type I and Type II diabetes mellitus in the cat. Am J Vet Res 54 (3), 463-467 PubMed.
  • Miller A B, Nelson R W, Kirk C A et al (1992) Effect of glipizide on serum insulin and glucose concentrations in healthy cats. Res Vet Sci 52 (2), 177-181 PubMed.

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