Читать книгу Diabetes For Dummies - Рубин Алан Л. - Страница 9

The body has three sources of energy: protein, fat, and carbohydrates. I discuss the first two sources in greater detail in Chapter 8, but I tackle the third one now. Sugar is a carbohydrate. Many different kinds of sugars exist in nature, but glucose, the sugar that has the starring role in the body, provides a source of instant energy so that muscles can move and important chemical reactions can take place. Table sugar, or sucrose, is actually two different kinds of sugar – glucose and fructose – linked together. Fructose is the type of sugar found in fruits and vegetables. Because fructose is sweeter than glucose, sucrose (the combination of fructose and glucose) is sweeter than glucose alone as well. Therefore, your taste buds don’t need as much sucrose or fructose to get the same sweet taste of glucose.

For many years, scientists have debated the role of sugar in the causation of diabetes. Now the evidence seems conclusive. Too much sugar leads to diabetes. In a study of 175 countries over the last decade, increased sugar in the food supply was linked to higher diabetes rates, regardless of obesity. The greater the level of sugar in the food supply, the higher the level of diabetes. The longer a high level of sugar persisted in the food supply, the higher the level of diabetes. The incidence of diabetes decreases as the sugar in the food supply decreases. Increased consumption of sugar precedes diabetes. How much is too much? Researchers haven’t established this amount, but the US Department of Agriculture recommends no more than 10 teaspoons of added sugar (sugar not normally found in fruits, vegetables, and dairy) per day. One 12-ounce can of soda has that much added sugar. Most Americans eat more than twice that amount.

In order to understand the symptoms of diabetes, you need to know a little about the way the body normally handles glucose and what happens when things go wrong. A hormone called insulin finely controls the level of glucose in your blood. A hormone is a chemical substance made in one part of the body that travels (usually through the bloodstream) to a distant part of the body where it performs its work. In the case of insulin, that work is to act like a key to open a cell (such as a muscle, fat, or liver cell) so that glucose can enter. If glucose can’t enter the cell, it can provide no energy to the body.

Insulin is essential for growth. In addition to providing the key to entry of glucose into the cell, insulin is considered the builder hormone because it enables fat and muscle to form. It promotes the storage of glucose in a form called glycogen for use when fuel is not coming in. It also blocks the breakdown of protein. Without insulin, you do not survive for long.

With this fine-tuning, your body keeps the level of glucose pretty steady at about 60 to 100 mg/dl (3.3 to 6.4 mmol/L) all the time.

Your glucose starts to rise in your blood when you don’t have a sufficient amount of insulin or when your insulin is not working effectively (see Chapter 3). When your glucose rises above 180 mg/dl (10.0 mmol/L), glucose begins to spill into the urine and make it sweet. Up to that point, the kidneys, the filters for the blood, are able to extract the glucose before it enters your urine. The loss of glucose into the urine leads to many of the short-term complications of diabetes. (See Chapter 4 for more on short-term complications.)