Unstable diabetes

Hi to all! I'm a new member. My cat Tilica a male 13 years old was diagnosed with diabetes 3 months ago . I started with insulin Humalog mix 25 but didn't work, Mixtrad 30 too. From the late November I have used Lantus but still isnt'working, sometimes his BG higher values are >500 mg/dl . It's very strange that after the insulin shoot BG increases. For example today at 9 AM preshoot insulin BG was 344 mg/dl 2 hours later 328 mg/dl and after another 3 hours rosed up at 383!! In the meanwhile he ate 20 g Royal Diabetic.
What cand I do? I need your advices , please.
Andreea from Romania

 

Welcome! We can help you figure this out if you post on the main health forum. Ask any questions you have over there.