GLARGINE INSULIN: SOMETHING NEW FOR CATS
Achieving regulation in the diabetic cat can be tricky. In most cats, finding an insulin that lasts long enough is a substantial problem. PZI insulin has been withdrawn from the market as has Humulin U. Presently, only glargine insulin (brand name Lantus®) is the only long-acting insulin available commercially. Glargine is approved only as a human product but its use is rapidly becoming common in the cat.
In human diabetes mellitus, the trend has been towards the use of ultra-short acting synthetic insulin (like Humilog®) at meal time and a once a day long-acting peakless insulin (namely glargine insulin) to provide a general blood sugar control throughout the day. Glargine insulin is readily available at any drug store and is designed to be long-acting to provide a diabetic person with a "tone" of sugar control that lasts all day long. The million dollar question is this: how well does it work for cats. So far, studies show it works pretty well and in new diagnosed diabetic cats, it seems to provide such good control (when used in combination with a low carbohydrate diet) that many cats revert to a non-diabetic status in a matter of weeks (in one study, six out of seven cats were in remission after only 4 weeks of glargine therapy). Is it too good to be true?
Before getting too excited, it is important to realize that diabetic remission is about good regulation early in the course of the disease rather than having a magic product. Further, feline use of glargine is still new enough that many veterinarians do not have extensive experience using it and it is a bit different than previously available insulin products.
- Even though glargine is a long acting insulin, it probably will need to be given twice a day just like other insulins.
- Glargine insulin cannot be diluted. The feline dose of insulin is generally only a few units of insulin and the gradations on an insulin syringe are tiny. With insulins other than glargine, dilution is possible to make measuring easier. The long-activity of glargine depends on the formation of small crystals where it is injected. This does not occur if one attempts to dilute glargine.
- Glargine is available in a Pen injector that measures one unit increments but it is expensive, expires in 1 month and cannot be refrigerated. The 10 ml bottle of glargine should be refrigerated to insure best activity as they will last at least 6 months when stored this way. Refrigeration is not as important with other insulin types. The 10 ml bottle of glargine will expire in 1 month if it is not kept refrigerated.
- With other insulins, as long as the cat is stable and eating, the owner is taught how to use insulin and the cat is sent home for a few weeks. A glucose curve is performed in 1-2 weeks to assess the success of the dose and insulin type chosen. Because some cats drop their blood sugars quickly, it is recommended that the cat starting glargine stay in the hospital for the first three days for blood sugar monitoring. Obviously this adds some expense.
- Because of the strong chance of a cat going into remission (i.e. becoming non-diabetic), it is important for the cat on glargine to have a curve weekly for the first 4 weeks of treatment. This many curves may not be needed when other insulins are used or, if they are needed, they need not be scheduled so close to one another. Most cats on glargine have achieved regulation after 10 days.
The high remission rates reported for diabetic cats
apply to cats newly diagnosed with diabetes.
Other cats who were switched to glargine for better
glucose control after having been diabetic for years
do not tend to revert to non-diabetic status.
Page last updated: 4/21/09