Diabetes For Dummies. Rubin Alan L.

High triglycerides

      ✔ A family history of diabetes

      ✔ Diabetes during a pregnancy or giving birth to a baby weighing more than 9 pounds

      

A study in the journal Diabetes Care in November 2007 showed that testing for prediabetes in overweight or obese people older than age 45 is highly cost effective if they then undergo lifestyle modification (see Chapters 7 through 12) or take medication if necessary. A study published in Diabetes Care in February 2014 showed that physically fit individuals with prediabetes have a lower death rate than unfit people with prediabetes, regardless of obesity.

Testing for prediabetes

Testing for prediabetes involves finding out your blood glucose level, the level of sugar in your blood. Prediabetes exists when the body’s blood glucose level is higher than normal but not high enough to meet the standard definition of diabetes mellitus (which I discuss in the section “Diagnosing diabetes through testing,” later in this chapter). Testing measures a random capillary blood glucose. If the level is greater than 100 milligrams per deciliter (mg/dl), a fasting plasma glucose or oral glucose tolerance test is performed. As of 2010, the American Diabetes Association recommends that the hemoglobin A1c (see the next section) can also be used for the definition. Table 2-1 shows the hemoglobin A1c and glucose levels that indicate prediabetes:

      ✔ If the glucose before the test (the fasting plasma glucose) is between 100 and 125 mg/dl, the person has impaired (abnormally high) fasting glucose, the glucose before eating (see Table 2-1). The glucose in the fasting state (no food for eight hours) is not normal, but it’s not high enough to diagnose diabetes.

      ✔ If the glucose is between 140 and 199 mg/dl at two hours after eating 75 grams of glucose, the person has impaired glucose tolerance. Both impaired fasting glucose and impaired glucose tolerance may be present.

      ✔ A hemoglobin A1c between 5.7 and 6.4 percent suggests prediabetes.

Table 2-1 Diagnosing Prediabetes

      

Mg/dl, or milligrams per deciliter, is the unit of measurement commonly used in the United States. The rest of the world uses the International System (SI), where the units are mmol/L, which means millimoles per liter. To get mmol/L, you divide mg/dl by 18. Therefore, 200 mg/dl equals 11.1 mmol/L.

      

Diagnosing prediabetes can be the best thing that ever happened to a person. It could be the wake-up call that he or she needs. The diagnosis may motivate a person to make crucial lifestyle changes, especially in diet and exercise, which have been shown to prevent the onset of diabetes in people with prediabetes. And for people whose prediabetes doesn’t respond to lifestyle changes, medication may accomplish the same thing.

      After a diagnosis of prediabetes is made, all the techniques described in Chapters 7 through 12 can help prevent the onset of clinical diabetes. If patients with prediabetes are left untreated, large numbers of these patients will develop diabetes over time. Preventing diabetes saves a person almost $13,700 in annual costs for the treatment of diabetes. And properly responding to a diagnosis of prediabetes prevented almost 20 percent of people with prediabetes from becoming diabetic.

      Detecting Diabetes

      When prediabetes becomes diabetes, the body’s blood glucose level registers even higher. In this section, I discuss the evidence for diabetes and the symptoms you may experience with diabetes.

Diagnosing diabetes through testing

      The standard definition of diabetes mellitus is excessive glucose in a blood sample. For years, doctors set this level fairly high. The standard level for normal glucose was lowered in 1997 because too many people were experiencing complications of diabetes even though they did not have the disease by the then-current standard. In November 2003, the standard level was modified again. In 2009, the International Expert Committee on Diagnosis and Classification of Diabetes Mellitus recommended using the hemoglobin A1c as a diagnostic criterion for diabetes, and the American Diabetes Association subsequently accepted the recommendation.

      After much discussion, many meetings, and the usual deliberations that surround a momentous decision, the American Diabetes Association published the new standard for diagnosis, which includes any one of the following four criteria:

      ✔ Hemoglobin A1c equal to or greater than 6.5 percent.

      ✔ Casual plasma glucose concentration greater than or equal to 200 mg/dl, along with symptoms of diabetes. Casual plasma glucose refers to the glucose level when the patient eats normally prior to the test. I discuss symptoms in the section “Examining the symptoms of diabetes” later in this chapter.

      ✔ Fasting plasma glucose (FPG) of greater than or equal to 126 mg/dl or 7 mmol/L. Fasting means that the patient has consumed no food for eight hours prior to the test.

      ✔ Blood glucose of greater than or equal to 200 mg/dl (11.1 mmol/L) when tested two hours (2-h PG) after ingesting 75 grams of glucose by mouth. This test has long been known as the oral glucose tolerance test. Although this time-consuming, cumbersome test is rarely done, it remains the gold standard for the diagnosis of diabetes.

      Following is another way to look at the criteria for diagnosis:

      ✔ FPG less than 100 mg/dl (5.5 mmol/L) is a normal fasting glucose.

      FPG greater than or equal to 100 mg/dl but less than 126 mg/dl (7.0 mmol/L) is impaired fasting glucose (indicating prediabetes).

      FPG equal to or greater than 126 mg/dl (7.0 mmol/L) gives a provisional diagnosis of diabetes.

      ✔ 2-h PG less than 140 mg/dl (7.8 mmol/L) is normal glucose tolerance.

      2-h PG greater than or equal to 140 mg/dl but less than 200 mg/dl (11.1 mmol/L) is impaired glucose tolerance.

      2-h PG equal to or greater than 200 mg/dl gives a provisional diagnosis of diabetes.

      ✔ Hemoglobin A1c equal to or greater than 6.5 percent gives a provisional diagnosis of diabetes. As the hemoglobin A1c rises from normal, the occurrence of diabetes rises with it. If the hemoglobin A1c is equal to or greater than 5.6, the patient has a threefold chance of developing diabetes in the next six years.

      

Testing positive for diabetes one time isn’t enough to confirm a diagnosis. Any one of the tests must be positive on another occasion to make a diagnosis of diabetes. I’ve had patients come to me with a diagnosis of diabetes after being tested only once, and a second test has shown the initial diagnosis to be incorrect.

Examining the symptoms of diabetes

      The following list contains the most common early symptoms of diabetes and how they occur. One or more of the following symptoms may be present when diabetes is diagnosed:

      ✔ Frequent urination and thirst: The glucose in the urine draws more water out of your blood, so more urine forms, making you feel the need to urinate more frequently. As the amount of water in your blood declines, you feel thirsty and drink much more frequently.

      ✔ Blurry vision: As the glucose level shifts from normal to very high, the lens of the eye swells due to water intake. This swelling prevents the eye from focusing light at the correct place, and blurring occurs.

      ✔ Extreme hunger: Inability to get energy in the form of glucose into the muscle cells that need it leads to a feeling of hunger despite all the glucose that is floating in