Understanding Your Blood Work Part II: Glucose
Glucose is the main sugar utilized by the body. It is actively absorbed by the intestinal tract and circulates in the
blood where it fuels all body cells, especially the brain. In fact, it is the brain’s preferred source of energy and there are complex neurological pathways to protect against a significant decline in blood sugar levels.
Although sugar provides the main source of energy that runs all body processes, recent research has shown it has other functions. Sugars, on the cell surface, are capable of enhancing recognition and communication between cells. They also play a critical role in immune function. Certain sugars are being used to aid in chemotherapy.
Glucose is part of a class of nutrients called carbohydrates. This class also contains the starches, which are long chains of sugar molecules. Carbohydrates are produced by photosynthesis in plants and therefore, our primary source of these compounds are fruits, vegetables, grains, legumes (like peas and beans) and tubers (like potatoes). In the body, starches are sliced by enzymes into the component sugars which are then converted to glucose in the liver.
After eating, there is a transient excess of glucose in the blood. A healthy liver will initially convert that sugar to a storage form called glycogen. Glycogen is found in the muscle and liver where it can be quickly converted back to glucose. If we eat more carbohydrates than can be used immediately or stored as glycogen, then the liver converts the remaining glucose to fatty acids and triglycerides to be stored in fat.
The glycemic index is a comparison of how quickly the sugars in food are absorbed into the bloodstream and available for use. The lower the number the slower the absorption and the more time the body has to handle the sugar without converting it to fat. Although not currently part of the nutritional panel on food containers, there has been discussion about adding the glycemic index. In general, we should choose foods with values under 55 and limit foods with values over 80. Athletes, needing a quick sugar boost, may choose foods with a higher index.
Insulin is a hormone produced by the pancreas. It is required to allow sugar to enter almost all cells of the body. A few notable exceptions are the lens of the eye and the inner lining of blood vessels. In these cells, sugar moves back and forth based on blood concentration alone. Hence, they are more sensitive to the effects of high blood sugar. When body cells become resistant to the effects of insulin or when insulin levels decline, blood sugar will rise. Conversely, if the pancreas produces too much insulin, blood sugars drop causing hypoglycemia.
By adjusting liver and pancreatic activity, the body is able to maintain a fairly stable blood sugar level. The foods we eat can profoundly affect blood sugar levels therefore, by convention, our normal ranges are based on the fasting state. Normal values are between 70 and 99 mg/dl.
A high fasting blood sugar suggests a risk for diabetes. This finding should be followed by another test called an A1c or glycohemoglobin. The A1c is based on the fact that every red blood cell gets a sugar coating as it circulates in the blood stream. The higher the average blood sugar, the thicker the coating becomes. By chemically measuring the coating, an estimate can be made of the average blood sugar for the past 3 to 4 months. An A1c less that 5.7 is normal. Between 5.7 and 6.4 suggests “pre-diabetes” (some difficulty in our body’s management of blood sugar). Values over 6.4 are consistent with diabetes.
A low blood sugar is called hypoglycemia and is associated with feelings of sluggishness, weakness, feeling faint, difficulty focusing and concentrating. In the extreme, it can result in death. People with hypoglycemia should be encouraged to eat small healthy meals 6 times daily.
Healthy Habits to Manage Blood Sugar:
1. Reduce concentrated sweets…cookies, candies and cakes.
2. Watch for hidden sugars in juices, soda and snacks. Non-diet soda is the leading source of sugar in the American diet.
3. Limit fruit juices to no more than 4-6 oz. daily. If you drink juice, choose 100% juice products. However, it is better to eat the whole fruit (orange, apple, etc) as it increases dietary fiber.
4. Increase regular exercise, as muscles prefer to burn sugar. Activity will decrease blood sugar levels.
5. Increasing dietary fiber slows the absorption of sugar and reduces the demand for insulin.
6. If there is a family history of diabetes, have your blood sugar tested regularly.
7. If the blood sugar is elevated, follow-up with an A1C.
8. If you are diabetic, aim for an A1c less than 6.4%. At this level, studies have shown no greater risk for diabetes associated health issues like heart disease, cataracts, stroke, etc.
9. Choose foods with a lower glycemic index. See chart for comparisons.