Glucose Toxicity and Hypoglycemia

Glucose Toxicity

Glucose toxicity occurs when insulin secretion is reduced by prolonged hyperglycemia. Prolonged hyperglycemia and diabetes mellitus can occur following prolonged and high-dose therapeutic use of glucocorticosteroids or exogenous progestogens. Progestogens have an antagonist effect on insulin, as they can lead to growth hormone excess and also have an affinity for glucocorticosteroid receptors.

Hypoglycemia in Feline Diabetes

Hypoglycemia occurs when the blood glucose level drops to 60 mg/dL or less. Hypoglycemia may be triggered by:

Insulin dose too high
Overlapping insulin dosage
Loss of appetite
Vomiting
Excessive exercise

This serious and potentially fatal condition can occur at any stage, even after stabilization has been achieved. In some instances, no particular trigger is identified.

Clinical Signs of Feline Hypoglycemia

The clinical signs of hypoglycemia that cat owners should be able to recognize are (in order of severity):

Hunger
Restlessness
Shivering
Incoordination
Disorientation
Convulsions and seizures
Coma

It’s important to alert your cat-owning clients that early signs of hypoglycemia may be subtle. Also, some cats will simply become very quiet and inappetent.

Coach your clients to watch for abnormal behaviors associated with hypoglycemia, and to contact you if they are concerned it is present.

Emergency Treatment of Hypoglycemia

Immediate oral administration of glucose solution or corn syrup (1 g per kg body weight). An alert animal may be fed a small amount of food. Animals that are collapsed should not have large volumes of fluid forced into their mouths as this may result in aspiration pneumonia: here it is preferable to rub a small amount of the glucose solution or corn syrup onto the animal’s gums or under its tongue.
Intravenous dextrose solution can be administered to effect in severe cases or if oral therapy has been ineffective.

Owners of pets with diabetes should always have a source of glucose readily available. Following the successful emergency administration of oral glucose, small amounts of food should be offered at intervals of 1–2 hours until the effects of the insulin overdose have been counteracted. Blood glucose monitoring should continue through entire duration of action of insulin (i.e. 12 hours for twice daily insulin and 24 hours for once daily insulin).

If the insulin dose is too high, reduce it by at least 10-50%. It may be necessary to construct a glucose curve to appropriately adjust the insulin dose.

Help Your Practice Manage Diabetes Mellitus

Check out these tools and resources to help manage feline diabetes.

Blood Glucose Curve Generator

Create a blood glucose curve to monitor and evaluate diabetes treatments.

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Client Discharge Form

Create a customized, printable form for clients about their new diagnosis.

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Diabetes Resources

Access online tools and more to support staff and pet parents.

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Important Safety Information:

Vetsulin^® should not be used in dogs known to have a systemic allergy to pork or pork products. Vetsulin is contraindicated during periods of hypoglycemia. Keep out of reach of children. As with all insulin products, careful patient monitoring for hypoglycemia and hyperglycemia is essential to attain and maintain adequate glycemic control and prevent associated complications. Overdosage can result in profound hypoglycemia and death. The safety and effectiveness of Vetsulin in puppies, breeding, pregnant, and lactating dogs has not been evaluated. See package insert for full information regarding contraindications, warnings, and precautions.

References:

1. Martin GJ, Rand JS. Pharmacology of a 40 IU/ml porcine lente insulin preparation in diabetic cats: findings during the first week and after 5 or 9 weeks of therapy. J Feline Med Surg. 2001;3(1):23–30. 2. Vetsulin^® (porcine insulin zinc suspension) [Freedom of Information Summary]. Millsboro, DE: Intervet Inc.; 2008. 3. Data on file, Merck Animal Health. 4. Graham PA, Nash AS, McKellar QA. Pharmacokinetics of porcine insulin zinc suspension in diabetic dogs. J Small Anim Pract. 1997;38(10):434–438. 5. Martin GJ, Rand JS. Pharmacokinetic and Pharmacodynamic Study of Caninsulin in Cats with Diabetes Mellitus. 2000: Internal Study Report. 6. Feldman EC, Nelson RW. Canine and Feline Endocrinology and Reproduction. 3rd ed. St. Louis, MO: Saunders; 2004:539–579. 7. Tennant B, ed. BSAVA Small Animal Formulary. 4th ed. Gloucestershire, UK: British Small Animal Veterinary Association; 2002. 8. Feldman EC, Nelson RW. Canine and Feline Endocrinology and Reproduction. 3rd ed. St. Louis, MO: Saunders; 2004:486–538. 9. Reusch C. Feline diabetes mellitus. In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine. 7th ed. St. Louis, MO: Saunders; 2010:1796–1816. 10. Nelson RW. Canine diabetes mellitus. In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine. 7th ed. St. Louis, MO: Saunders; 2010:1782–1796. 11. Burgaud S, Riant S, Piau N. Comparative laboratory evaluation of dose delivery using a veterinary insulin pen. In: Proceedings of the WSAVA/FECAVA/BSAVA congress; 12–15 April 2012; Birmingham, UK. Abstract 121. 12. Burgaud S, Guillot R, Harnois-Milon G. Clinical evaluation of a veterinary insulin pen in diabetic dogs. In: Proceedings of the WSAVA/ FECAVA/BSAVA congress; 12–15 April 2012; Birmingham, UK. Abstract 122. 13. Burgaud S, Guillot R, Harnois-Milon G. Clinical evaluation of a veterinary insulin pen in diabetic cats. In: Proceedings of the WSAVA/FECAVA/BSAVA congress; 12–15 April 2012; Birmingham, UK. Abstract 45. 14. Davison LJ, Walding B, Herrtage ME, Catchpole B. Anti-insulin antibodies in diabetic dogs before and after treatment with different insulin preparations. J Vet Intern Med. 2008;22:1317-1325. 15. Banfield State of Pet Health 2016 Report. p 12-13.

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