Hi Kauri, please see below the TR protocol rules for holding and reducing the dose. I don't believe he earned the last reduction from 0.5U to o.25U.
Phase 3: Holding the dose: aim to keep blood glucose concentration within 2.8–11.1 mmol/L (50–200 mg/dL) throughout the day
If blood glucose is <2.8 mmol/L (<50 mg/dL) - Reduce dose by 0.25–0.5 IU depending on if cat is on low or high dose of insulin
If nadir or peak blood glucose concentration is >11.1 mmol/L (>200 mg/dL) - Increase dose by 0.25–0.5 IU depending on if cat is on low or high dose of insulin and the degree of hyperglycemia
Phase 4: Reducing the dose: phase out insulin slowly by 0.25–0.5 IU depending on dose:
When the cat regularly (every day for at least 1 wk), has its lowest blood glucose concentration in the normal range of a healthy cat and stays less than 5.5 mmol/L (100 mg/dL) overall - Reduce dose by 0.25–0.5 IU depending on if cat is on low or high dose of insulin
If the nadir glucose concentration is 2.2–<2.8 mmol/L (40–<50 mg/dL) at least 3 times on separate days - Reduce dose by 0.25–0.5 IU depending on if cat is on low or high dose of insulin
If the cat decreases <2.2 mmol/L (<40 mg/dL) once - Reduce dose immediately by 0.25–0.5 IU depending on if cat is on low or high dose of insulin