Type I diabetes is a complex condition where restricting carbohydrates may not necessarily reduce hyperglycemia (high blood glucose) events. There is a dangerous downside counterbalancing the negligible benefits. The dieter significantly increases their risk of hypoglycemia (low blood glucose). Serious symptoms of hypoglycemia include heart palpitations, dizziness and coma.

I'm guessing a no carb diet could also imply high protein, to replace the carbohydrate calories. Too much protein (>20% of calories) is bad for Type I diabetics leading to a state known as microalbuminuria. In layman's terms: increased stress on your kidneys. More on this at: http://journal.diabetes.org/diabetesspectrum/00v13n3/pg132.h...

In summary, almost every (if not every) diabetes publication & specialist advises heavily against low/no carb diets, instead recommending a balanced diet.