Diabetes mellitus is one of the top two endocrinopathies in cats, with a prevalence estimated to be approximately 0.5% of cats seen in private practice. Successful management of diabetic cats involves insulin and dietary therapy, avoidance of corticosteroids if possible, and management of infections or concurrent diseases. As well, regular monitoring and client education are important. The goals of management are to:
Enable the cat to revert to a non-insulin dependent state
Minimize or eliminate clinical signs (polyuria, polydipsia, polyphagia)
Improve the cat's quality of life, normalize body weight and activity
Prevent complications (e.g., ketoacidosis, hypoglycemia, infections, neuropathy, etc.)
Owners must be properly trained to give insulin injections and educated on the important aspects of the disease in cats. All owners need to assess how well their cat is eating, drinking and general behavior. With early intervention and good glycemic control, diabetic remission was achieved in 84–100% of cats in two recent studies. The sooner glycemic control is reached, the higher the likelihood that diabetic remission can be achieved.
Current recommendations support the use of a high protein (> 30% DM), low carbohydrate (< 40% DM) diet for management of feline diabetes. Several studies have demonstrated an improvement in blood glucose (BG) levels and a decreased need for insulin therapy on this type of diet. Canned food is preferred in diabetic cats to maintain hydration, lower carbohydrate content, and improve satiety.
Both long-acting (e.g., glargine, determir, PZI) and intermediate-acting (e.g., porcine lente) products are available for treatment of diabetic cats (see Table 1). Most insulins are 100 units/ml (U100) and micro-fine or ultra-fine U100 syringes should be used. Since cats often require quite small doses of insulin, many owners find it helpful to use 3/10 cc (0.3 ml) syringes. However, Caninsulin/Vetsulin and ProZinc are U40 insulin, and U40 syringes must be used.
The greatest chance of achieving diabetic remission is prompt initiation of therapy with glargine or detemir insulin twice daily combined with dietary therapy and intensive monitoring to enable dose adjustments. However, remission has been achieved with all of the insulin types listed above and clinicians should become familiar with the usage of more than one type of insulin for feline patients. The starting dose for insulin should not exceed 0.25–0.5 U/kg BID. Regardless of the insulin type, most cats require twice daily administration. The maximum total starting dose, even for large cats, should not exceed 2 U/cat BID. Most cats are well regulated at doses from 0.2 to 0.8 U/kg.
'Spot' checks of blood glucose are not adequate or appropriate to maintain glycemic control of diabetic cats. Serial BG measurements (curves) are the most effective monitoring technique to establish what is happening with the cat's glucose homeostasis. Perceived benefits of home BG curves include obtaining samples in a less stressful environment where the cat's food intake should be normal, and the ability to perform more frequent BG monitoring. Long term compliance with home blood glucose monitoring is reportedly good. Home monitoring provides owners with more confidence in their ability to manage their cat's disease. There is no uniformly recognized BG monitoring protocol for diabetic cats. High remission rates have been achieved with weekly in-hospital monitoring of BG curves (stretching to every 2 weeks after the initial 4 weeks) as well as with home monitoring up to daily. Any insulin dose adjustments should be made with common sense. Suggested guidelines for dosage adjustments are shown in Table 2.
Once a cat achieves remission, ongoing BG monitoring should continue for the first month. Over the long term, urine glucose and water intake can be monitored to detect loss of euglycemia. If hyperglycemia is detected, insulin therapy should be re-started promptly to avoid further damage to pancreatic beta cells
Table 1. Comparison of Insulin Products for Treatment of Diabetes Mellitus in Cats.
|
Insulin brand
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Licensed in cats
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Manufacturer
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Formulation
|
Action
|
Dose*
|
|
ProZinc
|
Yes
|
Boehringer Ingelheim Vetmedica
|
U40
Recombinant PZI
|
Nadir 5–7 hours
Duration 8–9 hours
|
Start 0.25–0.5U/kg, BID;
Median maintenance dose 0.6 U/kg, BID
|
|
Vetsulin Caninsulin
|
Yes
|
Intervet
Schering Plough
|
U40
Porcine zinc
|
Nadir 4 hours
Duration 8–12 hours
|
Start 0.25–0.5 U/kg, BID;
Median maintenance dose 0.5 U/kg, BID
|
|
Lantus
|
No
|
Sanofi Aventis
|
U100
Insulin glargine
Recombinant human analog
|
Nadir and duration not known
|
Start 0.25–0.50 U/kg, BID
Median maintenance dose 2.5 U/cat, BID
|
|
Levemir
|
No
|
Novo Nordisk
|
U100
Insulin detemir
Recombinant human analog
|
Nadir and duration not known
|
Start 0.25–0.50 U/kg, BID
Median maintenance dose 1.75 U/cat, BID
|
*Based on lean body weight
From: Baral RM, Little S. Endocrine pancreatic disorders In: Little S, ed. The Cat: Clinical Medicine and Management. St. Louis: Elsevier Saunders, 2012;547–571.
Table 2. Suggested Guidelines for Insulin Dose Adjustment Based on Blood Glucose Curve Results.
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Insulin type
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Glucose concentration
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Insulin dose recommendation
|
|
Vetsulin,
Caninsulin
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Nadir < 3 mmol/L (54 mg/dL)
|
Reduce by 50%
|
|
Nadir 3-4.5 mmol/L(54–81 mg/dL)
|
Reduce by 1 U
|
|
Nadir 4.5–7 mmol/L (81–126 mg/dL)
|
Reduce by 0.5 U
|
|
Nadir 7–10 mmol/L (126–180 mg/dL)
|
No change
|
|
Nadir 10–12 mmol/L (180–216 mg/dL)
|
Increase by 0.5 U
|
|
Nadir > 13 mmol/L (234 mg/dL)
|
Increase by 1 U
|
|
Pre–insulin < 12 mmol/L (216 mg/dL)
|
Withhold and check for remission
|
|
Lantus
Levemir
ProZinc
|
Nadir 4.5–9 mmol/L (81–162 mg/dL)
|
No change
|
|
Nadir < 4.5 mmol/L (81 mg/dL)
|
Reduce by 0.5 U
|
|
Clinical hypoglycemia
|
Reduce by 50%
|
|
Pre-insulin < 4.5 mmol/L (81 mg/dL)
|
Withhold and check for remission
|
From: Baral RM, Little S. Endocrine pancreatic disorders In: Little S, ed. The Cat: Clinical Medicine and Management. St. Louis: Elsevier Saunders, 2012;547–571.
References
1. Cook A. Discovering the reasons underlying difficult-to-control diabetes in cats. Vet Med 2010;105:106–114.
2. Feldman EC. Diabetes remission in cats: which insulin is best? Comp Contin Edu Pract Vet 2009;31, uppl 7A.
3. Reusch C. Feline diabetes mellitus. Vet Focus 2011;21:9–16.
4. Rios L, Ward C. Feline diabetes mellitus: diagnosis, treatment, and monitoring. Compend Contin Educ Vet 2008;30:626–639.
5. Rucinsky R, Cook A, Haley S, et al. AAHA diabetes management guidelines. J Am Anim Hosp Assoc 2010;46:215–224.