Right, let's get one thing clear.
Detoxing is bulls***.
Your body has a variety of organs and systems designed to remove toxins from your system. Therefore any toxins in your body that can be removed will be removed by these organs. Anything that can't be removed will still be there regardless of whether or not you fast, eat cabbage soup, only eat foods beginning with the letter K or whatever other nonsense health advice someone with a flashy website selling supplements suggests.
'Detoxing' is not a reason to do ANYTHING, because it doesn't exist.
As for losing significant amounts of weight...let's get some clarity here.
The process by which anyone's body loses fat is by metabolising it. The process of fat metabolism, for everyone, regardless of whether or not you have diabetes, produces ketones. Ketones are like smoke. They are a waste product of burning fat. And just like smoke, ketones cannot tell you if the fire that is producing them is an intentional barbecue, or your house burning down.
If ketones build up in your blood, it causes DKA. You can reduce the amount of ketones in your blood by taking insulin. Insulin, in addition to allowing your body to process glucose, mops up ketones to prevent your blood becoming too acidic.
That makes me wonder about the people you've been talking to. Either they're simply just starving themselves - which means they will have ketones by definition as their bodies need energy - or worse, they're not taking their insulin. Losing weight by not taking insulin is a recognised, serious eating disorder and I suggest simply googling 'diabulemia' will reveal a litany of stories of men and women in their late 20s who did this sort of thing for a short time as teenagers....and now they're blind, missing limbs or dead.
Sorry to really get on the high horse and sound condescending on this but this water fasting idea is monumentally stupid. It won't detox you, any weight loss you achieve on it will be at incredible risk to your health, and I also guarantee that every one those T1s who's left a review suggesting it's wonderful will be blind, legless, impotent or 6 feet under in a decade. You do NOT want to join them.
If you want to detox or lose weight, you need to make smarter dietary choices and do more exercise. That may not be the answer you want to hear, but if you're unhappy with your body or your health, you can't magically fix that in a week by not eating.