In a way, I understand the way their struggle - Their bodies are screaming for foods that are designed to be addictive. They probably feel like they have no choice - and truthfully, in the midst of carb addiction, they don't really have much choice. The reasoning part of the mind is overwhelmed, desperate for their next "fix", at least in part because of the massive amounts of insulin their body is pumping out, plus whatever amount of additional insulin they're injecting in an attempt to handle the massive amount of blood sugar.

They may or may not have their come-to-Jesus moment when the doctor says "I'm very sorry, but you are going blind, a side effect of uncontrolled diabetes", or "we have no choice but to amputate". Even then, they may not be able to give up their drug of choice, because they've gone so many years feeding their addiction. They're already of the belief that carbs are the only thing they have to look forward to in their day, so how much stronger will that attitude be if they don't even have sight or walking to look forward to?

I know it's sad and very frustrating to watch. But you can't make the decision for them. It's not like you can have them committed to a rehab facility to get off carbs. And even if you could, think about how many drug addicts slip back into their drug habit after going through rehab. There's a huge psychological component that needs to be addressed, and while others can help the addict through that part, the addict still needs to really want to change.