The Ideal Blood Glucose Level For Running Thank you for asking that, because my number for a great run is different than my number sitting at this table right now. I like to start my runs at around 180 and most people would be shocked by that because it’s way out of target range, but it gives me a little leeway. I am not dropping down into a low blood sugar after 20 minutes of running. So for my half marathon I would be thrilled if I am somewhere between 160 and 180 to start my run.