I don't have an answer about your blood glucose Im sorry but Im also on day 4 of my own water fast! My urine until once this morning has been completely clear, how much water are you drinking? I also have back pain! Next week will seem only as hard as you make it, please forge through and in a couple of days you will probably be on an absolute high and so grateful for your own perseverance. The tiredness and hunger will go away! Good luck! In the same boat and cheering for you! :)