Starting insulin
Figure 2: Protocol for initiating insulin therapy in nonketotic diabetic dogs
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Ideally, the first dose of insulin should be administered in the hospital so that blood glucose concentrations can be monitored
for the first 12 to 24 hours. It is not necessary to achieve optimal control at this point. Instead, the goal is to provide
enough insulin to prevent ketosis without risking hypoglycemia. If anything, leaving the patient slightly hyperglycemic is
appropriate. Exercise and activity are likely to be higher at home than in the clinic setting, which will tend to drive glucose
concentrations down. When a ballpark insulin dose (i.e. enough to prevent ketosis but with minimal risk of hypoglycemia) has been established, the patient can be sent home. See
Figures 1 and 2 for detailed insulin therapy initiation protocols.
Follow-up care
It may take a few weeks to find the appropriate dose for a patient, and even well-controlled diabetics usually need periodic
adjustments. For dogs, I recommend a recheck after the first seven days of insulin therapy and then every six to eight weeks.
Any time the insulin dose is changed, reevaluate the patient within two weeks.
Figure 3: Monitoring diabetic cats receiving glargine
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Cats, particularly those receiving glargine, may go into remission within the first month of therapy, so close monitoring
is needed to identify the return of endogenous insulin production. Check the glucose concentrations (both pre-insulin and
nadir) on a weekly basis for the first month; decrease the insulin dose or discontinue therapy if hypoglycemia (glucose <
70 mg/dl) is identified or if the pre-insulin glucose concentration is < 180 mg/dl (see Figure 3).
At-home monitoring
A veterinary-specific glucose monitor (AlphaTRAK—Abbott Laboratories) is now available and provides rapid glucose measurement
with a single drop of blood. A 22-ga needle or a lancet device is used to puncture the skin, generally on the pinna or lip,
and the capillary action strip draws the sample into the machine. Many clients can easily learn to do this at home and are
able to check their pets' blood glucose concentrations without the inconvenience and expense of a visit to the veterinarian's
office. Cats particularly benefit from at-home monitoring, as stress hyperglycemia is avoided. Even if clients are reluctant
to check glucose concentrations on a regular basis, the ability to measure a glucose concentration if the pet is unwell or
acting strangely can be a lifesaver.
I do not encourage owners to change insulin doses based solely on at-home glucose measurements. Rather, the results should
be added to other information such as weight, thirst, hunger, urine output, and energy levels before dose adjustments are
made.
If owners are unwilling or unable to measure blood glucose concentrations at home, they can purchase urine dipsticks for glucose
and ketone detection. If ketones are frequently noted, the patient should be rechecked by the veterinarian. Most dogs with
well-regulated diabetes have mild glycosuria most of the day; any patient with persistently high urine glucose concentrations
or negative urine glucose concentrations is probably receiving an inappropriate insulin dose and should be examined. Do not
instruct owners to increase the insulin dose if substantial glycosuria is noted, as many patients that are receiving too much
insulin have periods of rebound hyperglycemia with subsequent spillage of glucose into the urine. Instead, owners should regard
this as an indication for a visit to the hospital and a full evaluation.
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