CVC Highlight: 8 tips to make life easier for owners of diabetic cats

Managing diabetes mellitus is a huge commitment for pet owners and can be a daunting task. Here are eight tips that can make life easier for the owners of diabetic pets.

Dr. Ellen N. Behrend

1. The quicker diabetes is controlled, the more likely remission will occur.

In a study evaluating remission in diabetic cats initially treated with insulin, 55 diabetic cats were included whose owners followed a highly intensive monitoring and blood glucose regulation protocol using insulin glargine and a low carbohydrate diet.1 Remission was achieved in 35 cats (64%). Cats that had received glucocorticoid treatment within six months prior to a diagnosis of diabetes mellitus, that required a lower maximum insulin dose, or that were intensively managed using glargine within six months of diagnosis were more likely to achieve remission, while cats with a peripheral neuropathy present at diagnosis (such as difficulty climbing stairs or a plantigrade stance) were less likely to do so.

2. Diet is important, and canned food is preferred.

Veterinary low carbohydrate-high protein therapeutic diets such as Purina Veterinary Diets DM (Nestlé Purina) or Prescription Diet m/d (Hill's Pet Nutrition) are the first-choice dietary recommendation in most cats with diabetes mellitus.2-4 However, a carefully selected over-the-counter high protein-low carbohydrate diet can provide the same degree of effective glycemic control as therapeutic diets do when financial constraints are present or when a cat will not readily eat a veterinary therapeutic diet.5 Many canned over-the-counter diets are relatively low in carbohydrate content (< 5 g/100 kcal), but information must be obtained from the manufacturer on specific brands and flavors to ensure that the goal nutrient composition is being met. Most dry over-the-counter diets are higher in carbohydrate content. Thus, if a therapeutic dry veterinary low carbohydrate-high protein diet is not an option, it may, unfortunately, be more difficult to identify a good-quality dry food with low carbohydrate content.

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3. Make giving insulin part of a pleasant experience for the cat—and the owner.

Insulin syringes, as compared with other types, are recommended because of the small needle size, but a needle prick can still be an unpleasant sensation. A good practice is to make the injections part of a good experience. For diabetic pets that are meal-fed and enjoy their food, inject them as they are eating and when they are close to finishing the meal. For others, owners can give the injections while doing a pleasurable activity. My cat Madison loved getting brushed every day. When he became diabetic, I started brushing him twice daily, and I gave him the injection midway through each brushing.

For any patient that needs a small amount of insulin, 0.3- or 0.5-ml insulin syringes should be used for accurate dosing. These are referred to as low-dose syringes. The scale on the syringe is easier to read for small doses.

The site of insulin injection is important. An appropriate location must be chosen, as absorption of insulin from various sites in the body differs. In dogs and cats, the dorsal neck, or the scruff, has commonly been used as an injection site, but this location may not be ideal because of low blood flow and increased fibrosis caused by repeated injections. A better option may be to administer the insulin along the lateral abdomen and thorax. The chosen area should be rotated daily to prevent fibrosis at an injection site.6

4. Oral hypoglycemic agents are less likely than insulin to work in cats.

The only oral agent that has shown success in diabetic cats is glipizide. It is a sulfonylurea antidiabetic agent that works by increasing insulin release. The long-term success rate is estimated to be approximately 35%7,8; which cats will respond cannot be predicted. The ideal patient for treatment with glipizide is a stable, nonketotic diabetic cat of optimum to obese body weight that has mild clinical signs with no complicating diseases. Patients that are emaciated, dehydrated, debilitated, have concomitant disease, or have recently lost > 10% of their body weight are not good candidates. Glipizide can be tried in any cat whose owners refuse to give injections.

It can take up to 12 to 16 weeks to know if glipizide will work. If no response is seen after that time, administration should be stopped and insulin therapy instituted. To me, this is the big problem with glipizide. It is not known exactly at what point glucose toxicity becomes irreversible, but the sooner diabetic control is obtained, the better (see above). Empirically, taking 12 to 16 weeks trying glipizide is worrying.

Other oral hypoglycemic agents do not hold much promise for treatment of diabetes mellitus in cats, including metformin, vanadium, chromium, and the glitazones. Acarbose can potentially be used in combination with insulin depending on the diet. If a high protein diet is not possible in a diabetic cat, feeding a more standard diet and administering acarbose may achieve the same goal.9 The dose is 12.5 to 25 mg/cat given twice daily with meals. Side effects are dose-dependent and include flatulence, semi-formed stools, or diarrhea.

5. It's important to perform blood glucose curves.

Glucose curves are not perfect: They can be affected by deviation from normal routine and can vary from day to day.10,11 Therefore, glucose curves should always be interpreted in light of clinical signs. (Also related to this variation is the important point that predicting the timing of a diabetic's nadir on the basis of previous serial glucose curve results and obtaining a single sample at that time are unlikely to give a reliable result, i.e. spot-checking does not provide helpful information.10) Stress hyperglycemia can also falsely elevate results.

However, glucose curves serve two very useful purposes that other techniques do not. First, they can clearly show clinically undetectable hypoglycemia. A glucose curve can document mild hypoglycemia that can be fixed before a seizure occurs. Thus, periodic curves can be helpful even in a seemingly well-controlled patient. Second, and more importantly, other diagnostic findings and clinical signs can suggest that control is lacking, but many reasons for poor control exist, including too low and too high a dose of insulin. The only way to know how to change the therapy to gain control is by performing a glucose curve.

6. The importance of home monitoring cannot be overemphasized!

One of the most crucial parts of judging the appropriateness of a dose, especially in cats, which are prone to stress hyperglycemia as a species, is by monitoring clinical signs. If a diabetic is not polyuric, polydipsic, or polyphagic and its weight is stable or increasing, it is usually well-controlled.

Measuring urine glucose at home can aid in monitoring. Glucotest (Nestlé Purina) is my preferred option for monitoring urine glucose at home in cats. First, urine glucose concentrations can be determined as needed to aid in assessing glycemic control, especially when other data are conflicting. Consistently negative readings on urine glucose may indicate that insulin doses are either adequate or excessive. Then a serial blood glucose curve will differentiate between adequate insulin therapy and excessive doses that could result in hypoglycemia. Uniformly high urine glucose readings coupled with unresolved clinical signs indicate that the insulin dose is inappropriately low.6 Second, urine glucose concentrations can be determined regularly (at least weekly) to help assess ongoing control. Changes in urine glucose concentrations may alert the owner and clinician to loss of glycemic control and a need for reevaluation.

To avoid some of the problems associated with in-hospital blood glucose curves, performance of glucose curves at home has taken on new importance. Home curves are likely the most accurate. For home glucose curves, it is not necessary for venous blood to be collected. Capillary blood is suitable.12 Choices of sites are the ear, gum, footpads, or elbow callus (dogs). I do not recommend using the gum and footpads because of the associated pain. It should also be recognized that glucose curves can vary from day to day when done at home as well.13 Two types of lancing devices are available. If using conventional automatic devices designed for pricking human fingertips, choose a device with a variable needle depth. The appropriate depth for each patient can then be used.14 A needle can be used, especially if the marginal ear vein is the site of blood collection. Glucometers that require minimal amounts of blood as well as those that sip the blood into the strip are desirable.

Training owners to perform home glucose curves takes time. Not all owners are suited to perform such a task. A small study of nine owners of diabetic dogs (n=7) and cats (n=2) indicated that, at least in that population, the most frequently encountered problems were the need for more than one puncture to obtain a blood drop, the creation of a sufficient blood drop, the need for assistance in restraining the pet, and the resistance of the pet.15 Two dogs became more resistant over time, and the owners abandoned the technique. The two cats became more compliant, especially because the technique was performed in a place chosen by the cat.15

7. When you perform a glucose curve, normal routine must be maintained.

The purpose of a glucose curve is to determine how a particular dose of insulin is performing given a specific diet and schedule. Thus, routine must be adhered to. Admittedly, the normal routine is difficult to maintain with a patient in the hospital or even if the dog or cat is being "poked" every two hours at home. However, the standard procedures must be adhered to as much as possible.

In the beginning, it is important for a veterinarian or technician to ensure that the insulin is being given correctly. That means an owner should give the insulin in front of the veterinarian, which may mean a deviation from schedule at that point. Once administration issues are no longer a concern, it is still desirable to have the insulin given in the hospital so pre-insulin blood glucose can be measured. However, keeping the schedule usually trumps all.

8. Know the signs of hypoglycemia and what to do.

One of the most dangerous aspects of diabetes is the possibility of causing hypoglycemia. The first signs are often subtle and include muscle tremors, nervousness, restlessness, and hunger. Then, as the central nervous system becomes "starved" for glucose, lethargy, weakness, ataxia, bizarre behavior, seizures, and coma can develop. Owners should always have a high-glucose syrup (e.g. Karo or honey) on hand to give their pets. If signs are mild, feeding a meal can be sufficient. The cat should be taken to a veterinarian immediately, or the blood glucose should be checked at home if the owner is capable of doing so. First, the presence of hypoglycemia should be documented, if possible. Second, once hypoglycemia develops in a treated diabetic, it can take days to resolve, so monitoring, and potentially hospitalization and treatment, are necessary. It is always better to treat if unsure.

REFERENCES

1. Roomp K, Rand JS. Intensive blood glucose control is safe and effective in diabetic cats using home monitoring and treatment with glargine. J Feline Med Surg 2009;11(8):668-682.

2. Bennett N, Greco DS, Peterson ME. Comparison of a low carbohydrate versus high fiber diet in cats with diabetes mellitus (abst). J Vet Intern Med 2001;15:297.

3. Frank G, Anderson W, Pazak H, et al. Use of a high-protein diet in the management of feline diabetes mellitus. Vet Ther 2001;2(3):238-246.

4. Mazzaferro EM, Greco DS, Turner AS, et al. Treatment of feline diabetes mellitus using an a-glucosidase inhibitor and a low-carbohydrate diet. J Feline Med Surg 2003;5(3):183-189.

5. Hall TD, Mahony O, Rozanski EA, et al. Effects of diet on glucose control in cats with diabetes mellitus treated with twice daily insulin glargine. J Feline Med Surg 2008;11(2):125-130.

6. Greco DS, Broussard JD, Peterson ME. Insulin therapy. Vet Clin North Am Small Anim Pract 1995(3);25:677-689.

7. 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 1997;210(6):772-777.

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

9. Singh R, Rand JS, Morton JM. Switching to an ultra-low carbohydrate diet has a similar effect on postprandial blood glucose concentrations to administering acarbose to healthy cats fed a high carbohydrate diet (abst). J Vet Intern Med 2006;20:726.

10. Fleeman LM, Rand JS. Evaluation of day-to-day variability of serial blood glucose concentration curves in diabetic dogs. J Am Vet Med Assoc 2003;222(3):317-321.

11. Ristic JME, Herrtage ME, Walti-Lauger SMM, et al. Evaluation of a continuous glucose monitoring system in cats with diabetes mellitus. J Feline Med Surg 2005;7(3):153-162.

12. Casella M, Wess G, Hassig M, et al. Home monitoring of blood glucose concentration by owners of diabetic dogs. J Small Anim Pract 2003;44(7):298-305.

13. Alt N, Kley S, Haessig M, et al. Day-to-day variability of blood glucose concentration curves generated at home in cats with diabetes mellitus. J Am Vet Med Assoc 2007;230(7):1011-1017.

14. Reusch CE, Wess G, Casella M. Home monitoring of blood glucose concentration in the management of diabetes mellitus. Compend Contin Educ Pract Vet 2001;23:544-556.

15. Van de Maele I, Rogier N, Daminet S. Retrospective study of owners' perception on home monitoring of blood glucose in diabetic dogs and cats. Can Vet J 2005;46(8):718-723.

Ellen N. Behrend, VMD, PhD, DACVIM

Joezy Griffin Professor

Department of Clinical Sciences

College of Veterinary Medicine

Auburn University, Auburn, AL 36849