An informal survey was taken on the Feline Diabetes Message Board on June 17, 2002 and again on July 26, 2002.
On the first date, the question was simply "How much insulin is your regulated cat getting?" and members quickly proposed adding weight and diet questions.
The second survey was more specific, asking: for the amount, frequency (twice a day assumed), type of insulin, weight of cat, and composition of diet (low carbohydrate, dry, mixed were suggested as categories, but many people gave detailed responses).
Regulation was not formally defined, but is largely understood by
members of the board to mean that the cat's blood glucose generally
ranges between 100 and 300 mg/dl over the course of a day, and
typically has a nadir in the
low 100's. It is likely that some respondents did not understand
and two responses were eliminated when it became clear that the cat
dropped below 300 mg/dl.
Number of observations: 69 observations on 64 cats (there were duplicates for a small number of cats who were regulated separately on high- and low-carb diets).
Types of insulin: PZI (of various varieties, mostly animal-based) and Humulin Lente were the most popular types of insulin, with Humulin Ultralente coming in third. Together, these three types covered 72% of the respondents.
Lente/Ultralente comb. 3
UK Lente 2
Lente Iletin 1
Summary of doses: SID doses (5 cats) were divided by 2 for comparison purposes. Of the cats who were getting insulin (5 zero-dose cats not analyzed here), the mean dose was 3.0 units BID, and the median was 2.5 units BID. Values ranged from .125 units BID to 11 units BID. 16% of the cats needed 1 unit BID or less, and 36% were getting 2 units BID or less.
Relationship between dose and weight: There was a positive relationship between dose and weight, although this disappeared after controlling for diet and insulin type. Further examination indicated that the cats receiving a combination of Lente and Ultralente tended to be the heaviest, and also tended to have the highest overall doses.
Relationship between dose and insulin type: Generally, there was no relationship between dose and insulin type, with the exception of the Lente + Ultralente cats. The source of PZI (BR, BCP, UK, Humulin) was also not related to dose.
Relationship between dose and diet: There was a very strong relationship between insulin dose and general dietary type (p<0.001, Kruskal-Wallis test).
The means of the high-carbohydrate, mixed, and unknown groups were not signficantly different from each other; however, the low sample size makes it difficult to detect differences. Controlling for insulin type and weight, and including the zero-dose cats, the cats on a low-carbohydrate diet had a significantly lower mean daily dose than the other three diets (p<.05, Tukey's test; p for high-carbohydrate diet vs low-carbohydrate diet = .0002). Even removing the zero-dose cats, the low-carbohydrate group had lower mean doses than the high-carbohydrate group (p=.0035).
Standard deviation of error term = 1.75 units.Interpretation of results: Vets need to be very cautious with the initial dose of insulin, especially if the cat is on a low-carbohydrate diet. Even 2 units twice a day is too high for a starting dose, since almost half of our regulated cats on low-carb diets are below that dose. There may be some leeway for larger cats, but there's not enough information on variability to ensure that this is the case.
Redacted raw data
|Dose||Freq||Insulin Type|| PZI
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