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rel="nofollow" href="#litres_trial_promo">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.)

      Understanding the Hemoglobin A1c

      Your blood glucose level is the level of sugar in your blood, a key measure of diabetes. Individual blood glucose tests are great for deciding how you’re doing at that moment and what to do to make it better, but they do not give the big picture. They are just a moment in time. Glucose can change a great deal even in 30 minutes. What you need is a test that gives an integrated picture of many days, weeks, or even months of blood glucose levels. The test that accomplishes this important task is called the hemoglobin A1c.

      Hemoglobin is a protein that carries oxygen around the body and drops it off wherever it’s needed to help in all the chemical reactions that are constantly taking place. The hemoglobin is packaged within red blood cells that live in the bloodstream for 60 to 90 days. As the blood circulates, glucose in the blood attaches to the hemoglobin and stays attached. It attaches in several different ways to the hemoglobin, and the total of all the hemoglobin attached to glucose is called glycohemoglobin. Glycohemoglobin normally makes up about 6 percent of the hemoglobin in the blood. The largest fraction, two-thirds of the glycohemoglobin, is in the form called hemoglobin A1c, making it easiest to measure. The rest of the hemoglobin is made up of hemoglobin A1a and A1b.

      The more glucose in the blood, the more glycohemoglobins form. Because red blood cells carrying glycohemoglobin remain in the blood for two to three months, glycohemoglobin is a reflection of the glucose control over the entire time period and not just the second that a single glucose test reflects.

      Hemoglobin A1c has a number of advantages over the variety of glucose tests for diagnosing diabetes, which I discuss in the later section “Diagnosing diabetes through testing.” Hemoglobin A1c is now as well standardized as glucose testing, and it has the following benefits:

      ✔ A1c reflects chronic high blood glucose rather than a few seconds in time.

      ✔ A1c has been found to reflect future complications (see Chapter 5) better than fasting glucose.

      ✔ Fasting isn’t necessary, and acute changes like diet and exercise don’t affect A1c.

      ✔ A1c is not as affected by sample delays on the way to or in the lab.

      ✔ A1c is also used to follow the course of diabetes, so the level of treatment needed is immediately understood.

      ✔ A1c is cost-effective, because no further testing is immediately necessary when results are abnormal (whereas an abnormal glucose test requires another glucose or A1c as the next test).

      Following are some disadvantages of hemoglobin A1c:

      ✔ Abnormal glucose after eating is a better predictor of heart disease than A1c.

      ✔ Some subjects with anemia, a recent blood transfusion, and abnormal hemoglobin types (there are several types of hemoglobin) produce an unreliable A1c result.

      ✔ Different ethnic groups have different levels for their abnormal A1c.

      According to one study, in the United States, hemoglobin A1c detects that diabetes is present in one in every five people admitted to a hospital for any reason without a diagnosis of diabetes.

      Getting a Wake-Up Call from Prediabetes

      Diabetes doesn’t suddenly appear one day without previous notification from your body. For a period of time, which may last up to ten years, you may not quite achieve the criteria for a diagnosis of diabetes but not be quite normal either. During this time, you have what’s called prediabetes.

      A person with prediabetes doesn’t usually develop eye disease, kidney disease, or nerve damage (all potential complications of diabetes, which I discuss in Chapter 5). However, a person with prediabetes has a much greater risk of developing heart disease and brain attacks than someone with entirely normal blood glucose levels. Prediabetes has a lot in common with insulin-resistance syndrome, also known as the metabolic syndrome, which I discuss in Chapter 5. The following two sections take the mystery out of whether you may have prediabetes by giving you some guidelines on when to get tested as well as explaining what testing for prediabetes involves.

Knowing whether you should get tested

      Approximately 90 million people in the United States have prediabetes, although most of them don’t know it. Testing for prediabetes is a good idea for everyone over the age of 45. I also recommend getting tested if you’re under 45 and overweight or eat more than ten teaspoons of added sugar daily and have one or more of the following risk factors:

      ✔ A high-risk ethnic group: African American, Hispanic, Asian, or Native American

      ✔ High blood pressure

      ✔ Low HDL (“good”

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