Just Ask the Expert: A tough feline diabetes case
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Q: We have an approximately 15-yr-old MN DSH clinic cat who has diabetes. I "rescued" him from his owners who were no longer giving him insulin or keeping him on Purina DM. He has been on glargine b.i.d. up to 7 units. His best control was on 5U b.i.d., and his glucose levels were 200mg/dl all day. On 7U b.i.d. his levels were 300. I suspected Somogyi overswing so I cut him back to 4U b.i.d. and increased him to 5U after his glucose levels went from 300 pre-insulin to 560 in 9 hours. He eats a controlled amount of Hill’s m/d dry and DM canned. His weight has gone from 11.5 lb in January (when owner wasn't treating) to 18 lb!
I'd appreciate any advice please. I think that with such high glucose levels he would not be gaining weight. His latest curve on July 7 started at 244 and ended in 12 hours at 400. There seems to be no nadir during the day. Of course he's PU/PD. Should I just use fructosamine to monitor him?
At his current body weight of 18 lb it looks like he is receiving about 0.6 units/kg of glargine b.i.d. This is slightly higher than we see in most cats where the average dose is 0.25 – 0.5 units/kg b.i.d.
Since glargine is a basal insulin you really will not see a lot of swing in the blood glucose levels over the day, as there are not going to be large swings in his serum insulin levels throughout the day. This is not the case with other insulin preparations such as NPH, PZI, or Lente where we tend to see peaks and troughs and where a combination of 12-hour blood glucose curves and fructosamine levels were needed to address insulin dose in animals with poor glucose control.
Based on the glucose curve obtained on July 7 in conjunction with the persistent clinical signs of polyuria and polydipsia I would suggest the following:
I would then adjust the insulin dose as follows. These recommendations for cats are based on our experience as well as on the data generated by Dr. Jacquie Rand at the University of Queensland.
The other issue is the weight. Make sure you are following the manufacturer’s feeding recommendation and that you are feeding the amount of calories intended for his ideal body weight. Some cats will gain weight on the high protein/low carbohydrate diets if they are not fed the appropriate amount of calories since they are very palatable and calorically dense. Keep us posted and let us know how things go from here.
Dave Bruyette, DVM, DACVIM
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