When you are referring to blood glucose levels, it is the amount or concentration of glucose in the human body which should be normally in the range of 4 and 6 millimoles per liter (mmol/L). If you are suffering from diabetes you are experiencing levels outside these limits. Higher glucose levels do not always mean you are diabetic, as they may be caused due to several other health reasons. However, whatever may be the cause, it is necessary to maintain the levels within the range as very high or low levels may cause damage to your small blood vessels or develop other risks.

Normal Blood glucose levels:

The total amount of glucose circulating in the human blood is about 3.3 to 7g for an average adult assuming his blood volume to be 5 liters. The blood sugar levels are regulated by the human body as part of a metabolic homeostasis. Glucose which is the primary source of energy for the body cells gets transported via the bloodstream from intestines or liver to the body cells. Blood glucose levels are higher immediately after meals. Ideally the values are 4 to 7mmol/L before meals, less than 10mmol/L immediately after meals and 8mmol/L at bedtime. They are usually the lowest in the morning before you have the first meal of the day. Unless with larger intervals between meals or a substantial carbohydrate content in the recent meal the sugar levels remain within a narrow range of about 3.9 mmol/L or 80 mg/dl to 6.0 mmol/L or 110 mg/dl. It may shoot up temporarily to 140 mg/dl or 141 mg/dl after eating.

Health effects

Failure to keep the blood glucose levels in the normal range may lead to either high or low blood sugar levels. High levels or hyperglycemia is caused when you have sugar levels much higher than the normal range. Persistent hyperglycemia may even lead to diabetes mellitus. Long term hyperglycemia causes health problems like diabetes, kidney damage, nerve damage etc. Low blood sugar level may cause hypoglycemia. Symptoms of hypoglycemia are lethargy, irritability, loss of consciousness, impaired mental function, and even brain damage in some cases.

Common tests

There are different tests that can be done to measure blood glucose levels.

* Fasting blood sugar (FBS):

This test is used to measure levels of glucose after you have not eaten for at least 8 hours. This is often the first test done to check for diabetes, though not the only one.

* Random blood sugar (RBS):

RBS measures the blood sugar regardless of when you have last eaten anything. Several tests may be conducted throughout the day. Random testing is useful in healthy people whose level do not vary widely throughout the day. Any variation may indicate a problem.

* 2 hour postprandial blood sugar:

This test is carried exactly 2 hours after you eat a meal.

* Oral glucose tolerance test:

This test is usually used to diagnose pre-diabetes and involves a series of measurements after you drink a sweet liquid which has glucose. It is most commonly use to diagnose gestational diabetes.

* HbA1c test:

This test is carried out to find out the average blood sugar levels over the previous six to eight weeks. It is basically useful to find out how you are controlling diabetes. HbA1c is a compound which is produced as a result of chemical reaction of hemoglobin and glucose in blood. It is also called as glycated hemoglobin. Consistent high levels cause HbA1c to rise. It is 6% of hemoglobin in people without diabetes, 7.5% with fair control of diabetes and 8.5% indicates poor control of diabetes.

Maintaining blood glucose levels in the specified normal range is necessary to keep you healthy and avoid any kind of future complications.



Thanks to Annie Duvall for contributing this article to our Diabetes blog:

Adult Onset Diabetes