Why is my dog's diabetes uncontrolled despite insulin treatment?

It sounds like his diabetes is not controlled well. I would start with a glucose check and a urine test. This will confirm if the sugar is still high and if he has ketones in his urine. Ketones can make them sicker and feel bad. They usually require IV fluids and a different, strong but shorter acting insulin to help get it under control they can also do blood work to check for cushings or a low thyroid or a secondary infection somewhere as these are common with diabetes and makes it harder to control diabetes until these are treated also. Once the blood sugar stop fluctating and staying high, his appetite will come back and the drinking slow down.

This could be a possibility. If your vet thinks Cushing she could be complicating her diabetes, you could consider testing her for cushings. If she definitely has cushings then you can start treating her for that. In the meantime, y'all will need to work on getting her diabetes under control. Another option would be to see if there is a specialist (internist) near you that could take over her case to help you get the DKA under control while also diagnosing and treating for cushings if needed. The main difference between a specialist and a general practitioner is that the specialist specializes in these complicated metabolic diseases and usually have facilities and specialized equipment that can care for them 24 hours if needed. If there is a cost concern and yall are unable to get the DKA under control and she is continuing to decline then yes, I would consider euthanasia. Unfortunately, even with intensive care and extensive testing, sometimes these guys don't improve and continue to decline no matter what we do. I know this is a difficult time and decision. Just know that you are doing the best thing for her whatever you decide. I hope this helps and know we are thinking of you. Hugs!

Poor Hershey. The increased urination could be due to her diabetes not being under control, but the increased grooming could be due to a medical illness like hyperthyroidism. I'd have her seen by her vet again for these issues.

Please try to bring her appointment forward to get her rechecked and her blood sugar levels controlled more effectively if possible. It may be necessary to change her insulin type but she should also be checked for infections/inflammation etc which may be altering her ability to regulate her condition

Lyme’s disease does not typically cause elevated blood glucose. So I don’t think it is Lymes dz. It sounds like Mia’s blood glucose is not being regulated properly. The goal is to get Mia’s blood glucose close to normal again or at least below 150. The veterinarian needs to check her glucose to see if she is on the appropriate dosage of insulin to get her blood sugar to decrease. If her sugar/glucose remains elevated then she will continue to have symptoms of diabetes(increased thirst/urination). There are several types of insulin that can be used in dogs. Some dogs respond better to one type vs another. Ask the vet to try a diff type of insulin if he/she can’t get the blood glucose regulated by increasing the dosage of insulin Mia is on. Once the blood glucose is regulated, she should start to act normal again. You can also get a glucometer to monitor the blood glucose at home. The vet can show you how to do this.

Yes, diabetic neuropathy could take months to improve once diabetes is under control. Considering the signs you are describing I think the glucose level may be still unregulated, as usually increased thirst and urination are the first signs to get under control.

Diabetes and Cushing's disease are caused by two different things, and both need to be treated. While you can see an increase in blood sugar when a dog has Cushing's, it's not as high as the blood sugar levels of diabetic patients. Gabe will need to be treated for both.