The reminder is the little clock on a timeline you see on your logging screen . It is meant to remind you to do something some time after your entry. You can use it to remind you of your post-meal BG or to take your shot at the end of a meal when you have a low… your imagination is the limit!
To set the reminder, just slide the clock at the top of the screen across the timeline until it reaches the time when you want to be reminded. At that time, the alarm will ring once then and you’ll get a notification. Just tap on it and enter your BG, shot or whatever else you set the reminder for!