Q and A: Blood Sugar

Q. I hear the term blood sugar a lot, but I don't really know what it means. How do you define it?

A. Blood sugar is a term that describes the simple form of sugar called glucose, which circulates in your bloodstream.

Q. Why do I have sugar in my blood?

A. The purpose of blood sugar is to provide "food" for your body's cells. Glucose is the sugar that provides energy to all cells in your body.

Q. Where does it come from?

A. Blood sugar comes from the foods you eat. Food is broken down into glucose in the digestion process.

Q. Where does it go?

A. Blood sugar is carried throughout your body by your blood. Some of it is used immediately for quick energy. The rest is converted into glycogen and stored in the liver and muscles to use as needed. Excess glucose is converted into fat and stored in adipose tissue.

Q. I don't eat around the clock. How does my blood sugar remain within the normal range when I'm sleeping, for example?

A. We need to have a steady supply of glucose, but your body is equipped to do that without any glucose coming in. It adjusts to the period of overnight fasting by obtaining the sugar from glycogen stored in the liver, so that the blood sugar level remains constant.

Q. I've heard the term hypoglycemia. What does it mean?

A. Hypoglycemia is a term describing a low level of glucose in the blood. Symptoms may include dizziness, profuse sweating, weakness, trembling, hunger, blurred vision, slurred speech, or headache. It occurs most frequently in people with diabetes who take insulin. It can also occur in those who do not have diabetes, but true hypoglycemia is very rare.

Q. What is diabetes?

A. It is a chronic disease that occurs when the body makes too little insulin or does not use the insulin it makes efficiently. Insulin is a hormone essential in bringing the blood sugar into the body's cells. As experts describe the process, insulin is like an escort. It goes into the bloodstream and "escorts" the glucose to the cells or the muscles or wherever it needs to go, and enables the sugar to enter the cell.

Q. Can low blood sugar make me feel faint if I skip a meal?

A. Surprisingly, the answer is no. Many people believe that their blood sugar levels drop when they skip a meal, bringing on dizziness. In studies in which researchers measured the blood sugar levels of people who have skipped a meal and said they felt dizzy, the levels were actually normal. Generally, the main way the body expresses its need for food is through hunger.

Q. Can a high intake of sugary foods cause my blood sugar levels to go out of balance and make me feel ill?

A. Most people are able to handle a sudden high sugar load through the delicate interaction of glucose and insulin. Even so, loading up on sugar might make you feel sick for other reasons. With lots of sugar in the system, there's a shift of fluids to the stomach and increased blood flow to the intestines. You might experience discomfort from all that fluid moving around, and also some post-meal lethargy as digestion occurs. It's even possible, with too much fluid shifting, to get diarrhea.

Q. I've heard parents say that when their kids eat a lot of sugar, they become hyperactive. Is that true?

A. Though many parents seem to observe this effect, studies have found no relationship between hyperactivity and increased sugar intake.

Q. Does eating too much sugar cause diabetes?

A. A common myth about diabetes is that eating too much sugar can trigger it. The only connection between sweets and diabetes is that excessive sugar intake can contribute to obesity. Obesity in turn is a major risk factor for type 2 diabetes. If you wish to avoid obesity, it's important to watch your intake calories whether from fats, starches, or sweets.

Q. How does insulin work?

A. Insulin is a hormone made in and released by the pancreas. Insulin is secreted when blood sugar starts to rise after a meal. It helps regulate blood sugar by bringing it into the cells of muscle and other tissues where it is used as fuel, to the liver where it is stored as glycogen for future use, and to fat tissue where it is stored as fat.

Q. Why do people with diabetes need to take insulin?

A: Not all people with diabetes need to take insulin. In type 1 diabetes, which usually develops early in life and affects about one in every 400 to 600 children and adolescents, the pancreas loses its ability to manufacture insulin. Blood sugar levels zoom out of control, but taking insulin helps. The more common form of diabetes--type 2--usually develops later in life and affects nearly 246 million Americans. People with this form of diabetes are insulin resistant (that is, they produce insulin, but their cells do not seem to obey its signal) or they produce too little insulin. People with type 2 diabetes may need to take insulin, but treatment also usually includes maintaining a healthy weight (a body mass index between 18.5 and 25), exercise, and sometimes, oral medications.

Q. What causes insulin resistance?

A. It's not fully understood, although obesity and physical inactivity are prime suspects. When people become overweight, their insulin receptors decrease or do not clearly transmit their signal inside the cell. The pancreas has to start pumping out insulin to make itself "heard." Likewise, when people are physically inactive, their tissues tend to be less sensitive to the effects of insulin.