Caution: Sleep Blood sugar can dip dangerously low during sleep for some people with type 1 diabetes. It's best to check your blood sugar level at bedtime and when you wake up. A snack before bed may help. For some people, blood sugar can rise in the morning -- even before eating -- due to changes in hormones or a drop in insulin levels. Regular testing is important. One option is a continuous blood glucose monitor, which can alert you to highs and lows.