Suggested Reading: Which insulin should I choose now that my options have dwindled?
Newly diagnosed cases1. Vetsulin (Intervet): This porcine-origin, zinc, lente insulin is intermediate-acting. Canine and porcine insulin have an identical amino acid sequence, which eliminates the theoretical complication of the dog developing anti-insulin antibodies that may adversely affect glycemic control. While the manufacturer recommends once-a-day initial dosing, I have not found this to be effective in most of our patients. I suggest an initial starting dose of 0.5 U/kg given subcutaneously twice a day. This insulin is available only at a concentration of 40 IU/ml, so make sure you provide U-40 insulin syringes to owners. Reassess the dog's clinical signs and perform a serial blood glucose curve one week after starting therapy.
3. PZI insulin: This long-acting, protamine zinc, beef-pork-origin insulin has, in my experience, not been more effective in controlling clinical signs in dogs than intermediate-acting insulins. This insulin is available only at a concentration of 40 IU/ml, so make sure you provide U-40 insulin syringes to owners. I recommend an initial starting dose of 0.5 U/kg given subcutaneously twice a day. If you select PZI insulin, I recommend that you use PZI Vet (Idexx), as compounded insulins can provide inconsistent treatment results. PZI is labeled for use in cats; for additional product information see the manufacturer's Web site: http://www.idexx.com/.
4. Insulin glargine: To date, no information on the use of glargine in diabetic dogs is available (see the discussion below regarding insulin glargine and cats).
In dogs receiving Humulin L Lente insulin, I recommend switching to either Vetsulin or Humulin N. The initial dose of Vetsulin or Humulin N will remain the same as the dose used with Humulin L, but be sure to reassess the dog's clinical signs and perform a serial blood glucose curve one week after changing insulin preparations.
Newly diagnosed cases
1. Insulin glargine (Lantus—Aventis): This is a modified, recombinant, long-acting insulin analogue approved for use in people. A study presented at the American College of Veterinary Internal Medicine annual meeting in 2005 showed a high rate of remission (8/8 in remission within four months, with 6/7 still in remission at one year) in feline diabetics with the use of glargine and a low-carbohydrate, high-protein diet. The recommended starting dose is 0.5 U/kg given subcutaneously twice a day if the fasting blood glucose concentration is greater than 360 mg/dl, or 0.25 U/kg given subcutaneously twice a day if the initial fasting blood glucose concentration is less than 360 mg/dl.1-3