You don't " need" to low carb as a Type 1 theoretically , but there are benefits from doing so, or at least reducing your carbs .the reasons as to why goes something like this :
To deal with carbs, you need to inject insulin. The higher the carb load, the more insulin you need. Higher doses of Insulin leads to weight gain, and possible insulin resistance. Higher body weight means you require yet more insulin. The higher the carb load/ insulin dosages , the more room there is for error with resultant hypo/ hyper.
That has been my experience anyway .
Signy