Insulin

From Dog

Insulin is an anabolic agent and an important regulator of the growth hormone and insulin-like growth factors[1].

In dogs, insulin is usually given as a treatment for diabetes mellitus.

Diabetes mellitus requires long-acting insulin injections to be given once or twice daily.

Each dog responds differently to insulin, so the proper choice of insulin type, dose, and frequency of administration needs to be individually determined. Selection of the appropriate insulin type, dose, and frequency of administration for an individual diabetic dog is ideally based on 18- to 24-hour blood glucose profiles. In order to perform a glucose profile, the dog is usually hospitalized, and following insulin administration, frequent determinations of blood glucose values are made throughout the day. The proper dose of insulin may change with time and may need to be adjusted based on blood glucose profiles, intermittent blood and urine sugar measurements, and response to therapy.

Over-dosage of insulin causes hypoglycemia, associated with weakness, listlessness, incoordination, convulsions and coma.

If hypoglycemia develops, the cat should immediately be offered its normal food if it is able to eat. Alternatively, a tablespoon of Karo syrup should be rubbed on the gums or, if the cat can swallow, given slowly by syringe into the mouth. Never force fingers, food, or fluids into the mouth of a convulsing or comatose cat. Your veterinarian should be contacted immediately if your cat experiences an episode of hypoglycemia so that further treatment instructions can be given and a modification of insulin administration, if necessary, can be made.

Dogs requiring excessively high insulin doses (greater than one to two units of insulin per pound per day) should be evaluated further. Other diseases may be underlying or complicating the diabetes mellitus and as a result, necessitate high insulin dosages. Problems with insulin injection, poor absorption or too rapid metabolism of insulin, or even insulin overdose are potential causes of an apparently excessive insulin requirement.

There are many types of insulin available. Insulin is derived from sources and have several durations of action. In the USA, the FDA has eliminated any animal-sourced insulin from the market. Thus, beef-pork and beef insulin are no longer available in the USA for humans. They are produced from recombinant technology and thus called 'Humulin' insulin.

Insulin presentations

The second part that affects the choice and efficacy of insulin is the speed of onset and the duration of effect of the insulin. There are four main categories (fast, intermediate, long acting and ultralong acting) and other combinations.

Type of Insulin Action Onset Maximum effect End effect
Regular fast 30 mins 1-5hrs 8hrs
Intermediate MPH 1.5hrs 4-12 hrs 24 hrs
Lente intermediate 2.5 hrs 7-15 hrs 24 hrs
Semilente intermediate 1.5 hrs 5-10hrs 16hrs
Combination 70%NPH, 30%regular 0.5 hrs 4-8 hrs 24 hrs
Ultralente long acting 4.0 hrs 10-30 hrs 36 hrs
  • Lispro - fast-acting effect - primarily reserved for ketoacidosis
  • Protamine zinc insulin (PZI) - medium acting effect
  • Caninsulin - intermediate acting porcine insulin with a peak activity of ~3hrs and duration of ~8hrs.
  • Glargine - long acting human rDNA insulin analogue that forms microprecipitates at the site of injection from which small amounts of insulin glargine are slowly released. Thus the glucose nadir occurs later than with PZI or lente.

References

  1. Bereket A et al (1999) Alterations in the growth hormone-insulin-like growth factor axis in insulin dependent diabetes mellitus. Horm Metab Res 31:172–181