The feline diabetic (Proceedings)


Friend or foe?

Is the feline diabetic patient every veterinarian's nightmare? Since diabetes mellitus is one of the most common endocrinopathies in cats, it is likely you will face this disease many times in your veterinary career. The focus of this presentation will be to discuss the problems you may encounter with your feline diabetic foes using case studies to illustrate how these feline diabetics can be your friends.


  • Clinical signs – water consumption, urination habits, appetite, activity, weight gain/loss

  • Blood glucose curves – useful to find nadir (low point), identify Somogyi effect

  • Some clients are willing to follow blood glucose readings at home, which has its advantages

  • and disadvantages. I still rely on my readings to adjust insulin doses.

  • Fructosamine levels – useful for all cats, especially fractious ones...!

  • Urine glucose monitoring – urine glucose test squares (Glucotest Feline Urinary Glucose

  • Detection System; Ralston Purina, St. Louis, MO) can be mixed in cat litter. Useful for non-insulin dependent patients to determine if glucosuria has recurred; persistent glucosuria suggests inadequate control and the need for reevaluation. Do not have owners adjust insulin levels based on urine glucose measurements.

Suspect insulin resistance when:

  • Dose of insulin is 6-8U (cat) q.12h and all BG levels >300 mg/dl

  • Dose of insulin is >2.2U/kg to maintain BG < 300 mg/dl

Insulin administration problems are the most common problems identified in poorly regulated diabetics.

  • Vary location of injection sites.

  • Shave injection sites.

  • Spend time training/testing clients on insulin administration. Make sure all the family members who will be giving the injections are trained.

  • Have the client obtain a new bottle of insulin every 4 weeks for all insulins except Lantus.

  • Lantus should remain potent for up to 6 months. If diabetic control is poor, have the client change to a new bottle every 2-3 months.

  • When poor diabetic control is present, review insulin administration techniques with the client and everyone giving the insulin injections. Don't forget to include the petsitter.

Every diabetic cat, especially those that are difficult to regulate, should have a full physical examination, complete diagnostic evaluation (CBC, biochemistry profile, serum T4, urinalysis), blood pressure measurement, and imaging studies (radiographs, ultrasound) to rule out concurrent diseases.

Causes of insulin resistance other than management problems:

  • Hyperthyroidism

  • Acromegaly

  • Bacterial infections (especially urinary)

  • Dental disease

  • Renal, hepatic, and cardiac insufficiency

  • Hyperadrenocorticism

  • Drugs (Corticosteroids, progestins)

  • Chronic pancreatitis

  • Toxoplasmosis

  • Exocrine pancreatic insufficiency

  • Neoplasia

  • Obesity

  • Hyperlipidemia

  • Diestrus

Treat/manage concurrent diseases (hyperthyroidism, inflammatory bowel disease (IBD), eosinophilic granuloma complex, chronic kidney disease, neoplasia).

You can use corticosteroids in diabetic pets when needed to treat other ongoing diseases such as IBD, asthma, allergic dermatopathy, eosinophilic ulcers or cancer.

  • Expect some degree of insulin resistance, requiring higher insulin doses.

  • Try to lower the corticosteroid dose to lowest effective level when/if possible.

Treatment options:

  • Prednisolone instead of prednisone

  • Budesonide

  • Inhalant corticosteroids.

Complications to be aware of in diabetic patients:

  • Infections, especially urinary tract (bacteria love the extra sugar in the urine)

  • Neuropathy due to poor diabetic control (long-standing)

  • Systemic hypertension

  • Don't forget systemic hypertension in diabetic patients

  • Can be a cause of acute blindness (retinal hemorrhages/detachment)

  • Can also be a silent killer

  • Blood pressure measurements -Goal: 145 mmHg or less (systolic)

Treatment of choice:

  • Varies based on doctor's experience and individual patient response

  • If a pet is not responding well to one therapy, try another one.

  • Short-acting insulin: Regular, primarily used in ketoacidotic cats

  • Intermediate-acting insulins: NPH

  • Long-acting insulins: PZI, Lantus

  • **My preference: Lantus 0.25-0.5U/kg q. 12-24h to start (long-acting insulin)**

Lantus - Insulin Glargine

This is the "insulin du Jour", but it is very effective at controlling diabetes mellitus in cats. Insulin Glargine is a long-lasting human insulin analog produced by recombinant DNA technology using a non-pathogenic strain of E coli. This insulin requires U-100 syringes. The bottle of insulin may remain potent for 2-6 months once opened.

Dose: 0.25 – 0.5 U/kg q 12 - 24 hours. Adjust dose as needed. Dose may decrease after 2 weeks of starting therapy (or sooner) in new diabetic patients.

Oral hypoglycemic drugs (cats): Limited use as single therapy; can be used in conjunction with insulin or other oral drugs to obtain better glycemic control.

Transition metals

Vanadium (Super Vanadyl Fuel (TwinLab)) ½ capsule once daily

Chromium 200 micrograms/cat daily

Alpha-glucosidase inhibitors

Acarbose 12.5-25 mg/cat with meals


Glipizide 2.5 – 5 mg/cat PO 2-3 times daily

Diet: Cats are carnivores.

Feed diet high in protein, low in carbohydrates (canned food preferred)

Kitten food

Purina DM

Prescription diet m/d

Some cats still do better on the high fiber diets (w/d, r/d).

Use high protein diets with caution in cats with evidence of chronic kidney disease.

Each cat is an individual and will respond differently to different diets.

  • Try to maintain consistent feeding schedule.

  • Let "nibbler" cats continue to nibble throughout the day and night.

  • Manage obesity!

Follow-up plan for diabetic patients:

  • Recheck the patient one week after starting insulin therapy. Perform blood glucose curve to determine nadir if using insulin other than Lantus. Adjust insulin based on these readings.

  • If using diet alone, recheck blood glucose after 3-4 weeks on the diet. ( fructosamine level).

  • Recheck pet every 1-2 weeks at nadir and adjust insulin based on blood sugar and clinical signs.

  • Consider running a fructosamine level when clinical signs are more normal and blood sugars are improving. I usually run a fructosamine level monthly until good control is obtained. This allows me to follow the trend in the levels. A steady decline should be seen. If not, review insulin administration or consider looking for complicating factors/diseases/diet.

  • Once the diabetic cat is well-controlled, recheck blood glucose and fructosamine levels every 3 months. Recheck full bloodwork, urinalysis, and blood pressure every 6 months.

Selected Readings

Appleton DJ, Rand JS, Sunvold GD, et al: Dietary chromium tripicolinate supplementation reduces glucose concentrations and improves glucose tolerance in normal-weight cats. J Feline Med Surg 4:13-25, 2002.

Behrend EN, Greco DS: Treatment of feline diabetes mellitus: Overview and therapy. Comp Cont Educ Pract Vet 22:423-439, 2000.

Behrend EN, Greco DS: Treatment of feline diabetes mellitus: Evaluation of treatment. Comp Cont Educ Pract Vet 22:440-452, 2000.

Berg RI, Nelson RW, Feldman EC, et al: Serum insulin-like growth factor-I concentration in cats with diabetes mellitus and acromegaly. J Vet Intern Med 21(5):892-898, 2007.

Biourge V, Nelson RW, Feldman EC, et al: Effect of weight gain and subsequent weight loss on glucose tolerance and insulin response in healthy cats. J Vet Intern Med 11:86-91, 1997.

Crenshaw KL, Peterson ME, Heeb LA, et al: Serum fructosamine concentration as an index of glycemia in cats with diabetes mellitus and stress hyperglycemia. J Vet Intern Med 10:360-364, 1996.

Elliott DA, Nelson RW, Reusch CE, et al: Comparison of serum fructosamine and blood glycosylated hemoglobin concentrations for assessment of glycemic control in cats with diabetes mellitus. J Am Vet Med Assoc 214:1794-1798, 1999.

Feldman EC, Nelson RW: Feline diabetes mellitus. In Feldman EC, Nelson RW (eds): Canine and Feline Endocrinology and Reproduction, 3rd ed. Philadelphia, W.B. Saunders, 2004, pp 539-579.

Feldman EC, Nelson RW: Diabetic ketoacidosis. In Feldman EC, Nelson RW (eds): Canine and Feline Endocrinology and Reproduction, 3rd ed. Philadelphia, W.B. Saunders, 2004, pp 580-615

Feldman EC, Nelson RW, Feldman MS: Intensive 50-week evaluation of glipizide administration in 50 cats with previously untreated diabetes mellitus. J Am Vet Med Assoc 210:772-777, 1997.

Goosens MMC, Nelson RW, Feldman EC, et al: Response to insulin treatment and survival in 104 cats with diabetes mellitus (1985-1995). J Vet Intern Med 12:1-6, 1998.

Gunn-Moore D: Feline endocrinopathies. Vet Clin Small Anim 35:171-210, 2005.

Kirk CA: Feline diabetes mellitus: low carbohydrates versus high fiber? Vet Clin North Am Small Anim Pract 36(6):1297-306, 2006.

Mazzaferro EM, Greco DS, Turner AS, et al: Treatment of feline diabetes mellitus using an alpha-glucosidase inhibitor and a low-carbohydrate diet. J Feline Med Surg 5:183-189, 2003.

Mayer-Roenne B, Goldstein R, Erb HN: Urinary tract infections in cats with hyperthyroidism, diabetes mellitus and chronic kidney disease. J Feline Med Surg 9(2):124-32, 2007.

Nelson, RW: Oral medications for treating diabetes mellitus in dogs and cats. J Small Anim Pract 41: 486-490, 2000.

Nelson RW, Lynn RC, Wagner-Mann CC, et al: Efficacy of protamine zinc insulin for treatment of diabetes mellitus in cats. J Am Vet Med Assoc 218:38-42, 2001.

Niessen SJM, Petrie G, Gaudino F, et al: Feline acromegaly: an underdiagnosed endocrinopathy? J Vet Intern Med 21(5):899-905, 2007.

Prahl A, Guptill L, Clickman NW, et al: Time trends and risk factors for diabetes mellitus in cats presented to veterinary teaching hospitals. J Vet Med Surg 9(5):351-8, 2007.

Rand JS, Marshall RD: Diabetes mellitus in cats. Vet Clin Small Anim 35:211-224, 2005.

Reusch CE, Kley S, Casella M: Home monitoring of the diabetic cat. J Feline Med Surg 8(2):119-27, 2006.

Weaver KE, Rozanski EA, Mahony OM, Chan DL, Freeman LM. Use of glargine and lente insulins in cats with diabetes mellitus. J Vet Intern Med. 20(2):234-8, 2006.

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