Diabetes mellitus is a common endocrine disease of cats that is probably increasing in prevalence. There is strong evidence that the majority of cats suffer a disorder similar to human type 2 diabetes mellitus. This is characterised by both insulin resistance and impaired insulin secretion. In cats, as in humans, remission is a possibility, particularly if those factors contributing to insulin resistance (such as obesity) and impaired insulin secretion (such as glucose toxicity) are effectively addressed.

Remission rates vary in different studies from 0 to 100%, but none are directly comparable. In practice, remission rates of between 30 and 50% are probably more realistic. From a review of the literature, it appears that dietary therapy (using a low-carbohydrate, high-protein diet) and the intensity of monitoring strategies (particularly those that attempt to tightly control blood glucose concentrations) are extremely important in achieving remission.¹ The type of insulin used may also play a role, but this appears to be of lesser importance. Many owners would prefer to know the likelihood of remission before choosing a given treatment protocol with an intense monitoring strategy. Unfortunately, it is difficult to predict which cats will go into remission and which will not, but generally if remission is to occur it will do so in 3–4 months. Not surprisingly, remission is more likely in cats that are less severely hyperglycaemic at diagnosis. Additionally, remission is more likely in cats intensively treated soon after (<6 months) first diagnosis, in cats recently treated with glucocorticoids, in older cats and in those without signs of peripheral neuropathy.² Gender, weight (including obesity), presence of diabetic ketoacidosis, renal disease or hyperthyroidism, and frequency of hypoglycaemia are not predictors of remission. Approximately 25–30% of cats in remission will relapse and most have evidence of impaired glucose tolerance or inappropriately high glucose concentrations.³ Repeat remission, although possible, becomes less likely. It may also be worthwhile testing for acromegaly early on, given it is associated with insulin resistance, thereby significantly decreasing the likelihood of remission. Acromegaly may be an underdiagnosed condition and has been recognised in 25% of diabetic cats, where only 1 in 4 was phenotypical of the disease.⁴ Treatment with insulin should be instituted for two weeks prior to testing for acromegaly.

References

1.  Gostelow R, Forcada Y, Graves T. Systematic review of feline diabetic remission: separating fact from opinion. Vet J. 2014;202:208–221.

2.  Zini E, Hafner M, Osto M. Predictors of clinical remission in cats with diabetes mellitus. J Vet Intern Med. 2010;24:1314–1321.

3.  Gottlieb S, Rand JS, Marshall R, et al. Glycemic status and predictors of relapse for diabetic cats in remission. J Vet Intern Med. 2015;43:245–249.

4.  Niessen SJM, Forcada Y, Mantis P, et al. Studying cat (Felis catus) diabetes: beware of the acromegalic imposter. PLoS One. 2015;10(5):e0127794.