(2020) Updates in Feline Diabetes Mellitus and Hypersomatrotropism

From Veterinary Clinics of North America: Small Animal Practice Volume 50, Issue 5, September 2020. Authors Dr. Linda Fleeman and Ruth Gostelow

This article (see attached) discusses a number of fairly new topics and concepts in feline DM.

Case 1: A sick diabetic cat with DKA, how he was accessed and treated in hospital. An interesting quote from the article "Importantly, DKA in cats with newly diagnosed DM does not affect survival time, and these cases can often go on to achieve diabetic remission". There is a discussion of fluid and electrolyte therapy, insulin therapy in hospital, including both rapid acting insulins and Lantus glargine given by IV. The cat was fitted with a continuous glucose monitor (Freestyle Libre). It does point to research that the CGM may be less accurate in cats where there is hypoglycemia, but cat detect low glucose values missed by intermittent testing and is complimentary to use of BG meters. The cat went into remission after 7 weeks.

Case 2: A cat with hypersomatotropism (HS) - the condition that causes acromegaly. The article talks about assessment, including some photos There are several conditions that can cause insulin resistance in cats (listed), though the cat's higher dose 10 units and still hyperglycemic means HS is more likely. Not all cats with with HS (the benign pituitary tumour) have outward clinical signs (acromegaly). The prevalence of HS may differ in by country. A study in the UK found HS occurring in 25% of diabetic cats, a study in Switzerland and Holland found it to be 18%. The cat had a serum IGF-1 test done, and found to be positive for HS. The article notes that some small percent of cats do not show changes to the pituitary with a CT scan or MRI, so they are not definitive diagnostics.

The article describes varies treatment options for HS, with advantages and disadvantages of each. This particular cat underwent hypophysectomy, or surgical removal of the pituitary gland at the Royal Veterinary Clinic. There is a description of follow up medications needed post surgery. The cat was fitted with the Libre and went OTJ 3 weeks post surgery.

Case 3: A cat with excessive glycemic variability, the term "brittle DM" has been used in the past. The cat had gone OTJ and relapsed and the caregiver could not get stable glycemic control in two years, in spite of changing insulin from Caninsulin to Lantus. To treat the cat, a Freestyle Libre was attached and the cat's insulin was changed to Toujeo, a glargine 300 U/mL insulin. Toujeo has longer and flatter action than other products. The cats clinical symptoms of DM reduced and the cat was better controlled without the clinical signs of hypo he'd seen before. Note, Toujeo can only be given via pen needles and not by drawing insulin from the pen with syringes. This does mean finer dosing is not possible.