Glargine is very similar to human insulin (the hormone varies slightly from species to species with regards to the location of certain amino acids) but has been modified in such a way as to precipitate (come out of solution) at body pH. This causes it to be released slowly and at a relatively constant rate. It has been called a “peakless” insulin in people. Abnormal peaks and valleys in blood sugar levels define poor diabetic control, so an insulin that maintains steadier blood sugar levels obviously has some value.
Despite its popularity in the treatment of diabetic cats, I had never heard of glargine being used to treat diabetes in dogs. However, a study published in the October 15, 2013 issue of the Journal of the American Veterinary Medical Association now has me excited about the possibility.
Researchers treated 10 diabetic dogs with an initial dose of 0.5 units glargine insulin per kilograms body weight injected under the skin twice daily. Five of the subjects had just been diagnosed with diabetes while the other five were poorly regulated while being given either porcine lente insulin or human NPH insulin. In addition to receiving glargine insulin, the dogs in the study were also fed a high fiber diet, which is a standard recommendation for diabetic dogs. The authors found the following:
"There was no significant difference between mean minimum and mean maximum blood glucose concentrations or between any of the blood glucose concentrations measured at other time points. This was true at the time of the first follow-up visit as well as when dogs had well-regulated diabetes mellitus. We therefore concluded that, in dogs, glargine insulin is a peakless insulin, which results in a relatively flat blood glucose concentration curve."
The rate of hypoglycemia in this study was quite high being seen in “7 of the 10 study dogs and in approximately 10% of the 281 blood glucose concentrations measured.” Therefore, the authors recommend that glargine insulin be started at a dose of 0.3 units per kilogram body weight twice daily. If an individual dog does not achieve adequate regulation at dose, it can always be gradually increased. Lowering the initial dose should decrease the number of hypoglycemic episodes associated with the use of glargine in dogs.
The authors concluded that “glargine insulin administered SC [under the skin] twice daily is an effective mode of treatment for dogs with naturally occurring diabetes mellitus and may be used as an alternative to other insulin preparations that have been shown to be effective in treatment of diabetes mellitus in dogs.” Diabetic management is such a balancing act that I wouldn’t recommend switching to glargine if your dog is doing well on another insulin preparation, but it is an intriguing option for newly diagnosed or poorly regulated diabetic dogs.