Type 1 diabetics should check their blood sugar levels before bed, before exercise, during exercise, and before and after meals and snacks, recommends Mayo Clinic. Type 2 diabetics should check their blood sugar before bedtime and before meals.
Checking blood sugar helps diabetics determine if they are keeping their diabetes under control, states Mayo Clinic. Testing blood sugar levels also helps diabetics determine how much of an effect meals and snacks have on blood sugar. Type 1 diabetics should check their blood sugar approximately four to eight times per day, while Type 2 diabetics are advised to check their blood sugar levels two or more times per day depending on their individual needs. In some cases, a Type 1 diabetic needs to check her blood sugar during the night.