Understanding Blood Sugar Levels: Normal Ranges & Significance

The level of glucose in the blood normally stays within a very narrow range. An abnormal blood sugar level can indicate a metabolic disorder such as diabetes, where the patient is unable to metabolize sugar.

Units of Measure

• The blood sugar level is commonly measured in units of milligrams of glucose per deciliter of blood (mg/dl). Millimoles per liter (mmol/l) is also a common unit of measure for blood glucose.

Normal Values

• The reference range for the blood glucose level is 80 mg/dl to 110 mg/dl, with 90 mg/dl being the mean. Divide these values by 18 to convert to units of mmol/l.

Meals

• The blood sugar level normally increases significantly after a meal as the food is broken down into glucose. The blood sugar level in non-diabetics reaches a peak of about 140 mg/dl approximately two hours after a meal.

Hyperglycemia

• A blood sugar level greater than 180 mg/dl taken two hours after a meal is generally defined as hyperglycemia. This glucose level is considered clinically significant and is one of the symptoms of diabetes.

Hypoglycemia

• Hypoglycemia is most often defined as a blood glucose level below 70 mg/dl, although it typically isn't symptomatic until the blood glucose level drops below 55.