The normal range for blood glucose measured six to eight hours after the last meal is 70 to 100 mg/dL (5.6 mmol/L), states WebMD. The range varies depending on the person's age, how far back the last meal was and how much food was consumed.
If blood glucose is tested two hours after eating, the normal blood glucose level is lower than 140 mg/dL (7.8 mmol/L) for people under 50. It is lower than 150 mg/dL (8.9 mmol/L) for those aged 50 to 60 and 160 mg/dL (8.9 mmol/L) for 60 years and older, states ABC News. Sugar levels tend to be higher after eating, which is why it is best to do the test before eating or after waking up.
Over time, high blood sugar levels can damage the body.