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    Blood Glucose

    blood glu·cose — blud GLOO-kohs

    Definition

    Blood glucose refers to the concentration of glucose (a simple sugar) circulating in your bloodstream. Glucose is your body's primary source of energy, derived from the carbohydrates you eat. After a meal, your digestive system breaks down carbohydrates into glucose, which enters the bloodstream and is then transported to cells throughout the body with the help of insulin, a hormone produced by the pancreas.

    Maintaining blood glucose within a healthy range is critical for normal body function. For most healthy adults, normal fasting blood glucose is between 70 and 99 mg/dL. Levels between 100 and 125 mg/dL indicate prediabetes, while levels of 126 mg/dL or higher on two separate tests indicate diabetes. After meals, blood glucose naturally rises but should return to near-fasting levels within two to three hours in healthy individuals.

    Blood glucose regulation is a complex process involving multiple hormones, organs, and feedback mechanisms. When blood sugar rises after eating, the pancreas releases insulin to help cells absorb glucose. When blood sugar drops between meals or during exercise, the pancreas releases glucagon, which signals the liver to release stored glucose. Disruption of this delicate balance — through insulin resistance, pancreatic dysfunction, or other factors — leads to the metabolic disorders we know as prediabetes and type 2 diabetes.

    Also Known As

    Blood sugarSerum glucose

    Key Facts

    • Normal fasting blood glucose is 70-99 mg/dL; prediabetes is 100-125 mg/dL; diabetes is 126+ mg/dL.
    • The hemoglobin A1c (HbA1c) test provides a 2-3 month average of blood glucose levels.
    • Continuous glucose monitors (CGMs) can track blood sugar levels in real-time throughout the day.
    • Exercise, sleep quality, stress, and meal timing all significantly affect blood glucose levels.
    • Approximately 96 million American adults have prediabetes, and more than 80% of them don't know it.

    How It Relates To Your Health

    Blood glucose monitoring is central to the management of both type 1 and type 2 diabetes, but it's also increasingly relevant for anyone interested in metabolic health. Regular fasting glucose tests and HbA1c measurements help identify prediabetes early — a critical window when lifestyle changes can prevent or significantly delay progression to full diabetes.

    Factors that help maintain healthy blood glucose include regular physical activity, a diet rich in fiber and low in refined carbohydrates, adequate sleep, stress management, and maintaining a healthy weight. If your blood glucose levels have been trending upward, these lifestyle modifications can be remarkably effective when implemented consistently.

    Sources

    1. Blood Sugar (Glucose) — MedlinePlus (NIH)
    2. All About Blood Glucose — American Diabetes Association
    3. Diabetes Tests — Centers for Disease Control and Prevention

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