Which of the following blood glucose levels is considered normal for an adult?

A blood glucose level of 80 mg/dL is considered normal for an adult. Typically, normal fasting blood glucose levels range from about 70 to 100 mg/dL. This range reflects the body's ability to maintain glucose homeostasis. When the body is functioning properly, it regulates blood glucose levels through hormones like insulin and glucagon, keeping them within a healthy range. A level of 80 mg/dL falls comfortably within this range, indicating good metabolic control and normal function.

In contrast, the other listed blood glucose levels indicate varying degrees of hyperglycemia or hypoglycemia. Levels at 150 mg/dL and 180 mg/dL are higher than the normal range, indicating potential issues with glucose metabolism, which may suggest prediabetes or diabetes if they are persistently observed. A level of 40 mg/dL is considered dangerously low and suggests hypoglycemia, which can cause significant symptoms and may require immediate intervention to prevent complications. Understanding these levels is crucial for recognizing and managing diabetic conditions effectively.