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.
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
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
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
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.