My understanding is this:
You have to start somewhere to figure out what your ratio will be, i.e. start w/1:15 or 1.5:15 or 2:15 and adjust accordingly until what you deliver (insulin) covers the carbs (gets your BG where you want it).
Everybody will be different...
The only reason your ratio will change would be if your weight (or some other factor) changes. Then you start playing w/ratios again.
As far as changing during the day, that prob has more to do w/activity changes during certain times of day, or types of food at meals.
One key thing to do: never eat a carb alone. Make sure you have a friend or family member close by...
Just kidding. Always include a protein source - esp at bfast, and snacks.
