What is a fasting blood test?

A fasting blood test is a laboratory examination of a sample of your blood taken from a vein (usually in your arm) after you have not eaten anything for at least eight hours and sometimes as long as 12 hours. Your doctor may also suggest that you don't drink anything other than water during this fasting time and may also advise you not to take any medications during your fasting period. Two common reasons for having a fasting blood test are to check the level of sugar (glucose) in your blood and to check the levels of cholesterol in your blood. In both cases the accuracy of your results may be affected by the food you eat. Fasting before your blood test can help to ensure accurate results.

Continue Learning about Diabetes


Diabetes mellitus (MEL-ih-tus), often referred to as diabetes, is characterized by high blood glucose (sugar) levels that result from the body’s inability to produce enough insulin and/or effectively utilize the insulin. Diabetes ...

is a serious, life-long condition and the sixth leading cause of death in the United States. Diabetes is a disorder of metabolism (the body's way of digesting food and converting it into energy). There are three forms of diabetes. Type 1 diabetes is an autoimmune disease that accounts for five- to 10-percent of all diagnosed cases of diabetes. Type 2 diabetes may account for 90- to 95-percent of all diagnosed cases. The third type of diabetes occurs in pregnancy and is referred to as gestational diabetes. Left untreated, gestational diabetes can cause health issues for pregnant women and their babies. People with diabetes can take preventive steps to control this disease and decrease the risk of further complications.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.