Like gas to a car, "blood sugar," or glucose, is the major source of fuel for the body. Without a steady glucose supply from food, the heart would not beat, brain neurons would not fire and death would quickly ensue. Normal glucose levels fluctuate throughout the day, but both low and high blood sugar can be life-threatening. Luckily, your body has a hormonal system that maintains normal glucose levels even while you sleep.
Normal Fasting Glucose
While professional opinions vary, the American College of Endocrinology and the American Association of Clinical Endocrinologists define normal fasting glucose as between 70 and 100 mg/dL of blood. A level under 70 mg/dL indicates hypoglycemia; 101 to 125 mg/dL, prediabetes; and greater than 125 mg/dL, diabetes. The hormones insulin and glucagon maintain normal blood glucose levels through a delicate balance of their opposing actions. Insulin removes and glucagon adds glucose to the blood as needed.
Normal Postprandial Glucose
Most of the body's glucose comes from carbohydrate-rich foods such as fruits, vegetables, legumes and whole grains. Postprandial, or following a meal, blood sugar levels rise as your body digests food and breaks carbohydrates down into glucose that, with the help of insulin, gets delivered to cells. No matter what he eats, a healthy person's glucose levels fall below 140 mg/dL one to two hours post-meal and back below 100 shortly thereafter.
Abnormal Glucose Risks
Poorly controlled blood sugar causes both short- and long-term complications. Going long periods without eating may cause hypoglycemia, characterized by symptoms of hunger, dizziness or weakness. Untreated hypoglycemia can lead to coma or death. Hyperglycemia usually indicates diabetes, and symptoms may include frequent urination and increased thirst. You may not notice symptoms, however, and a diagnosis requires blood tests. Left untreated, hyperglycemia from diabetes can lead to cardiovascular disease or kidney failure.
Maintaining Healthy Glucose Levels
While much of the body's physiologic regulation of glucose levels is beyond your control, you can help by practicing healthy behaviors. Exercising regularly and eating small, frequent meals that combine complex carbohydrates like fruits, vegetables, legumes and whole grains with lean proteins and healthy fats will help reduce extreme blood sugar swings. Not only will you feel sustained energy throughout the day, but you'll also nourish your body with nutrient-dense foods that promote lifelong health.
References
- "Endocrine Practice"; Diagnosis and Management of Prediabetes in the Continuum of Hyperglycemia: When Do the Risks of Diabetes Begin? A Consensus Statement From the American College of Endocrinology and the American Association of Clinical Endocrinologists; Alan J. Garber, M.D., Ph.D., et al.; 2008
- National Diabetes Information Clearinghouse: Hypoglycemia
