Feline diabetes mellitus: Important client communication points (Sponsored by Intervet Schering-Plough Animal Health)

Diabetes mellitus is one of the most common endocrine disorders in cats, affecting about one in 400 cats in the United States. Although it can affect cats of any breed, sex, or age, the disease is seen more often in older, obese, or neutered male cats.

Most cats diagnosed with diabetes require lifelong insulin treatment, and clear communication between the cat owner and veterinarian is vital to successful diabetes management.

Cats with diabetes often present to the veterinarian with classic clinical signs—polydipsia, polyuria, polyphagia, and weight loss—and the diagnosis is frequently made in the exam room using a glucometer and urine dipstick. The most important communication regarding feline diabetes occurs in those five minutes after the diagnosis. Many clients express shock and distress after hearing the diagnosis, and it is imperative that you allay their fears by explaining that the disorder is treatable and emphasizing that successful management requires a high level of care and strong commitment from the caregiver.

The instruction

In my experience, the biggest concerns clients have are the insulin injection process and the demanding injection schedule. Tell clients that caring for a diabetic cat requires a time, financial, and an emotional commitment. In rare instances, clients may decide that they are unwilling (or unable) to make the necessary commitments and may choose not to treat, but in most cases, clients accept the chronic nature of their cat's illness and want to learn how to manage the disorder at home.

If the client seems overwhelmed by the diagnosis and all of the new information being conveyed during the appointment, it may be prudent to schedule a separate appointment for insulin injection instruction a day or two following the diagnosis. This would allow clients a little time to ponder the cat's new medical status, and they are likely to be more attentive and focused and will probably come with a list of relevant questions. If the client is comfortable and accepting of the diagnosis, insulin injection instruction can begin immediately (see Table 1).

Table 1. Insulin preparation

The equipment

Use the proper syringe for the particular concentration of the insulin being used. Veterinary insulin preparations are available in U-100 (each ml contains 100 units) or U-40 (each ml contains 40 units) formulations. If you prescribe a U-40 product, you must also provide U-40 syringes for the client. However, no U-40 human insulin products currently exist, so human pharmacies, therefore, do not carry U-40 syringes. Tell clients they cannot use a U-100 syringe with a U-40 product because it will result in a significant underdosing of the patient.

It is vital to measure the insulin dose accurately. Show clients how to insert the needle through the rubber stopper of the bottle and how to remove air bubbles that may have collected in the syringe. When the syringe is held with the needle pointing upward, the dose of insulin should be read from the top of the plunger (Figure 1).

Figure 1. Proper measuring technique for insulin

The injection

In cats with a good body condition, the most common site of injection is the skin between the shoulder blades. In thin or emaciated cats, however, the shoulder blades protrude and make this site challenging for proper injection. If this is the case, choose an alternate site, such as the flank or hip area. A veterinarian or trained technician should demonstrate the injection technique to clients.

After demonstrating the technique, watch the client perform two or three injections. A vial of sterile vaccine diluent can be used in place of an insulin vial, and clients can practice mixing, measuring the dose, and injecting the insulin to the veterinarian's satisfaction.

Clients are sometimes unsure if their injection delivered the insulin—especially if the cat is long-haired. You can ease the process by clipping a patch of hair and creating a target area for the client, changing sites every few days to theoretically prevent injection-site fibrosis. If a client is unsure if the insulin went into the skin, or sees a drop of liquid at the injection site after injection, the client should skip that dose and proceed normally to the next scheduled injection. Skipping an occasional dose is usually harmless, but overdosing can be disastrous.

When discussing insulin and injection technique, suggest to the client that one person be designated the primary caregiver to reduce confusion that may develop with the cat's daily insulin dose. If a client's schedule demands that the injection duties be divided among family members, suggest that a calendar be posted in a central location (e.g., on the refrigerator where the insulin is kept) with "a.m." and "p.m." written in each day's space. When the insulin is injected, the appropriate box is checked. Affix a pen to the refrigerator door via a string to minimize the chances of the caregiver forgetting to check the box for lack of a pen.

Most cats require insulin injections twice a day, which should be given about 12 hours apart. Clients should make every attempt to give the injections at the designated time. When this requirement cannot be met, the client has a two-hour window before or after the scheduled injection in which they can administer the injection. If the client can't give the injection within the two hour window, it's best to skip the dose and resume the injections at the next scheduled time.

By this time, the client has realized that the days of providing a heaping bowl of dry food and an extra bowl of water and leaving the cat unattended for the weekend are over. However, because the cat requires lifelong medication does not mean the client can never take a vacation. Remind clients that most professional catsitters can proficiently administer insulin injections and that most veterinary hospitals offer boarding services, including the daily administration of insulin. In addition, clients can teach a close friend or trusted neighbor—not a child—to administer proper injections and perform proper feeding.

Hypoglycemia

Hypoglycemia is a potentially dangerous complication of diabetes management and its most common cause is insulin overdosage. The clinical signs of hypoglycemia—weakness, ataxia (best described to clients as a "drunken" gait), lethargy, staring into space, seizures, or coma—should be discussed thoroughly. Tell clients to immediately offer the cat its normal food if signs of hypoglycemia seem evident. If the cat is unable or unwilling to eat, rub corn syrup onto its gums or administer by syringe if the cat can swallow. Clients should never force food or corn syrup into the mouth of a seizuring or comatose cat. Signs of hypoglycemia, in most cases, will resolve within a few minutes. Tell clients to contact their veterinarian for instructions if the cat shows signs of hypoglycemia. If the cat shows signs after regular clinic hours, tell the client to take the cat to a local emergency clinic for evaluation.

Clients often find the description of hypoglycemia distressing. Assure clients that hypoglycemia episodes are uncommon, and the risk of hypoglycemia is minimized if the regulation process is started with a low insulin dose that is gradually increased based on the cat's response. The most common reason that I see for overdosage is when a family member gives an insulin injection, unaware that the injection has already been given.

Additional concerns for diabetic cats

Once regulated, most diabetic cats can remain reasonably healthy at home, but make clients aware that diabetic cats have an increased risk for illness and infection, especially bladder infection. Diabetic cats also have an increased risk of ketoacidosis and should be evaluated immediately by a veterinarian if they develop signs of vomiting, diarrhea, loss of appetite, or severe depression.

Inform the client about dietary issues concerning diabetic cats—a high-protein, low-carbohydrate diet has been shown to reduce insulin requirements and can achieve better diabetic control.1 These diets are available as prescription formulations that are carried by most veterinarians. Obesity is a major factor that affects insulin sensitivity, and obese cats should be fed these diets in an amount that helps the cat lose weight safely. A high-protein diet may be inappropriate for cats with concurrent chronic renal failure. A high-fiber diet is the next best thing if an overweight cat finds these diets unpalatable. Diabetic cats have been successfully managed with both types of diets, but trial and error is necessary to determine which diet works best for which cat.

Monitoring

Monitoring of feline diabetes has changed over the years. As an alternative to the glucose curve, serum fructosamine is a reflection of the cat's average blood glucose over the preceding two weeks. Tell owners of newly diagnosed diabetic cats that a baseline serum fructosamine level is necessary to establish the starting point and that serum fructosamine levels need to be checked two weeks after any change in insulin dosage is made to determine if the new insulin dose is adequately controlling the diabetes.

Fructosamine can be thought of as the "coarse tuning knob." In the majority of cats, the clinical signs will begin to resolve as the fructosamine approaches the high end of the reference range. This usually takes two or three visits, as a typical diabetic cat requires one to four units of insulin twice a day. Cats that have physical exam findings and clinical signs at odds with the serum fructosamine assays may need to have a glucose curve run for more fine tuning.

Advances in home monitoring systems are leading some veterinarians to recommend that blood glucose curves be obtained at home. Blood glucose concentrations are measured at home by collecting capillary blood from a cat's ear using a human lancing device. This can be demonstrated in the office for the client. Collection of blood from the ear does not appear to be painful to most cats, and the puncture sites are barely visible, even after multiple collections.

Conclusion

Caring for a diabetic cat can be emotional for everyone involved, and clients may wonder if the insulin injections and dietary changes are stressful to the cat. Assure clients that these changes are difficult at first but are necessary and life-saving and will soon become part of daily life for the client and the cat. Cats do not develop diabetic cataracts like dogs do, and the chronic complications that afflict people with diabetes (e.g., kidney disease, blood vessel disease, and coronary artery disease) are uncommon in diabetic cats.2

Many clients instinctively react negatively upon receiving the diagnosis of diabetes in their cat, assume that things are hopeless, and tune out everything the doctor says from that point forward. It is imperative, therefore, that the client be immediately reassured that although diabetes is not curable, the prognosis is good, and most cats live a normal healthy life for many years. Clarifying this point in the first few minutes after the diagnosis is made can make the difference between life and death for the cat.

References

1. Bennett N, Greco DS, Peterson ME, et al. 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 2006;8:73-84.

2. Basher AW, Roberts SM. Ocular manifestations of diabetes mellitus: diabetic cataracts in dogs. Vet Clin North Am Small Anim Pract 1995;25:661-676.

Online tools

For knowledgeable support and practical resources for both you and your pet owners, visit www.vetsulin.com.