I am sorry Flip is not feeling well. Many cats that were diabetic and eating dry food turn around and become nonndiabetic when switched to canned food only.
Please read article written by a feline vet:
It is possible Flip has hypokalemia. That is a fancy way of saying low potassium. It causes muscle weakness and lethargy.
The cure is a potassium supplement which his vet can provide:
In the meantime feed him canned food sprinkle an eighth of tsp of Mrs Dash salt substitute once a day.
If he gets dehydrated give him tuna water drained from the can.
Please let me know how he is doing .
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