Understanding Blood Sugar Levels

Blood sugar levels show the concentration of glucose in the blood stream. Glucose comes to the blood from the food we eat and then is converted into energy with the help of insulin, a hormone produced by the pancreas. Blood sugar levels show how well one’s metabolism and homeostatic mechanism work and help diagnose prediabetes, insulin resistance, type 1 and 2 diabetes and other medical conditions.

Although in a healthy body blood sugar concentration stays within a narrow range, it changes throughout the day, depending on a number of factors, such as general health state and current diseases and conditions, time of the day when the test is taken, fasting or having meals, absence or presence of active mental work or physical activity. Correspondingly, accepted normal blood sugar levels for different periods differ. Stable levels or glucose are maintained by a complex of interacting systems in the body called homeostatic mechanism. Failure to regulate blood sugar levels results in persistently high blood glucose levels or hyperglycemia; or low levels - hypoglycemia. Stresses, illnesses, surgeries or traumas, strokes, heart attacks, even taking certain medications may temporary raise glucose concentration in the blood stream.

Blood Sugar Levels Tests

The two major tests used to measure blood sugar levels to used to diagnose diabetes and pre-diabetes are fasting blood sugar test and glucose tolerance test. The unit of measure used are milligrams per deciliter (ml/dl) or millimoles per litre (mmol/L).

  • Fasting blood sugar level test is taken after at least 8 hours of fasting before the first meal of the day (nothing except for water is allowed before that), usually in the morning. This is one of the major tests used to diagnose diabetes and pre-diabetes.
  • Glucose tolerance test is done after taking a glucose drink.
  • Blood sugar levels 2 hours after eating (2-hour postprandial blood sugar). Always taken exactly 2 hours after the start of meal, otherwise the result cannot be authentic. This is not a primary test in diagnosing diabetes and pre-diabetes.

Additionally, random blood glucose tests may be taken throughout the day, as a rule by those who have been diagnosed with diabetes and need to have their blood sugar under control.

Blood Sugar Samples Used

Blood sugar is measured either in whole blood or plasma/serum (the samples that exclude erythrocytes high in proteins). Historically, glucose was measured in whole blood. Currently,laboratories use plasma or serum glucose levels to measure glucose. These are cleaner samples that have more glucose dissolved thus having higher concentration of it. The ratio of glucose concentration in whole blood to plasma/serum levels is 1.15, so it’s necessary to pay attention which specific sample is used for the test - whole blood or plasma when assessing blood sugar levels and setting targets.

Blood Sugar Levels During Pregnancy

Keeping blood sugar levels under control is of particular importance if you are pregnant. The problem is that even women who have never been diagnosed with diabetes may develop gestational diabetes due to hormone level changes. This condition may go away without doing any damage to the woman’s health, but the baby may be put at serious risk. Please visit blood sugar during pregnancy page for more information.

We hope this site helps you better understand blood sugar levels and maintains yours within healthy ranges .