Pre-Diabetes Glossary

This List defines terms that people with prediabetes commonly encounter as they learn more about the condition.

Autoimmune disease

A disease in which the body attacks itself. Type 1 diabetes is an autoimmune disease in which T-cells, the body’s immune system “warriors,” attack the body’s own tissues, mistaking them for intruders such as germs or viruses. Specifically, the T-cells destroy the beta cells in the pancreas, which produce insulin. Type 2 diabetes is not an autoimmune disease.

Beta cells 

The cells in the pancreas that produce insulin. People with prediabetes still produce insulin in their beta cells, but their bodies are becoming less sensitive and more resistant to the insulin.   

Blood glucose (blood sugar)

Glucose is the main sugar that the body uses to fuel cellular activity. It is a simple sugar, called a monosaccharide. The body can produce glucose from fat, protein, or carbohydrates, but carbohydrates are the primary source of glucose.

To move from the bloodstream into the cells of the body, glucose needs assistance from the hormone insulin. When the body is no longer producing insulin (type 1 diabetes) or is resistant and insensitive to insulin (type 2 diabetes), the amount of glucose in the bloodstream becomes very high. An excess of glucose causes inflammation that can lead to the organ and nerve damage that are common side effects of diabetes.

BMI (body mass index)

A calculation used to determine if a person is of normal weight, overweight, or obese. To find BMI, you multiply a person’s weight by 703 and then divide it by the person’s height squared (the number times itself).

For example, a person who weighs 150 lbs. and is 68 inches tall would divide 105,450 (150 lbs. x 703) by 4,624 (68 inches x 68 inches). The resulting BMI, 22.8, is considered normal.

Generally speaking, BMI numbers are rated as follows:

  •  18.5 to 24.9 = normal or “optimal.” Less than 18.5 is considered underweight, and less than 16.5 is labeled “severely underweight.”
  •  25 to 29.9 = overweight
  •  30 to 34.9 = obese (Class 1)
  •  35 to 39.9 = obese (Class 2)
  •  40+ = obese (Class 3)

While BMI numbers are useful in helping healthcare providers assess risk, they do not take into account differences in body mass that can lead to misreading a patient’s true condition. For example, a small weightlifter who has immense muscles could be labeled overweight even though much of his body mass is not fat.

Effects of of type 2 diabetes

Type 2 diabetes poses a long-term danger to the people who have it. High blood sugar levels inflame the cardiovascular system, which over time can lead to a weakening of blood vessels or changes in their ability to transport blood properly. The end results can include stroke, heart attack, or heart disease.

High blood sugar also affects other organs. People with diabetes often have problems with their kidneys and retinas (the light-sensitive membranes at the back of eyes). Kidney failure and degeneration of the retina-sometimes leading to partial or total blindness-are possible outcomes as diabetes “progresses” through the years.

Nerve damage is also common. Many people with diabetes suffer from neuropathy, the slow loss of feeling in their nerves, especially in their hands, legs, or feet. The loss of sensation is often associated with slower healing due to high blood sugar. As a result, people with diabetes run a high risk of severe injury to their limbs that can result in amputation.

Fasting blood glucose test

Until recently, this was the preferred test for determining if a person has prediabetes or diabetes. The test is a “snapshot” that shows how much glucose is in the bloodstream of a patient who has been fasting since midnight. Patients undertake the fast to give the body a chance to metabolize glucose and drop its level in the bloodstream to a volume that is the norm for them.

Although the test is reasonably accurate in most cases-the chances of a person with normal, non-diabetic blood glucose levels registering high levels are slim-there are cases where stress or other factors may spike the test results and give a false reading. Subsequent tests usually establish a true norm.

These days, healthcare providers increasingly are relying on the A1C test to assess a patient’s long-term blood glucose level.

A1C test

This test, which measures the amount of glycated hemoglobin in the bloodstream over a three-month period, is becoming the standard for determining a patient’s risk for type 2 diabetes.

Glycated hemoglobin is a substance that forms when glucose attaches to hemoglobin. (Hemoglobin is the part of red blood cells that carries oxygen.) The amount of glycated hemoglobin that accumulates over 90 days can reveal a patient’s average blood sugar level over that three-month period. The A1C’s ability to deliver this long-term information is one reason why it is supplanting the older fasting glucose test, which is a “snapshot” of a person’s blood glucose level at one moment in time.

The test requires blood drawn from a vein.

A1C numbers generally indicate the following:

  •  Below 5.7% = non-diabetes (some healthcare professionals become concerned when A1Cs rise above 5.5% because the normal range for people who do not have diabetes is 3.5% to 5.5%)
  •  5.7% to 6.4% = prediabetes or “at risk”
  •  6.5% or more = diabetes


When tissues become injured or irritated, the body responds by sending blood and immune system elements to the affected area, often creating congestion, swelling, and heat. This process, inflammation, is the immune system’s response to invading germs and viruses or irritating substances. Ideally, the inflammation destroys the invaders or neutralizes the offending substances, paving the way for eventual healing of the affected tissues.

But in diabetes, high blood sugar creates constant inflammation, a condition that if left unchecked can damage blood vessels, the heart, and other vital organs.


Insulin is a hormone produced and secreted by cells in the pancreas called beta cells. The hormone regulates the amount of sugar in the bloodstream and the rate at which the body metabolizes it. In type 1 diabetes, the body loses the ability to produce any insulin. In type 2 diabetes, the body may continue producing insulin, but either becomes less able to produce it or unable to use it.

Insulin resistance

The condition in which the body loses its ability to respond to insulin. Insulin resistance is typical in people with prediabetes or type 2 diabetes. The body may continue producing insulin, but it can no longer effectively use that insulin to control blood glucose levels.

Metabolic syndrome

A “cluster” of conditions that is often a precursor to type 2 diabetes. These can include insulin resistance, high cholesterol, high blood pressure, high blood sugar, and being overweight. While everybody who has metabolic syndrome can be said to have prediabetes, not everybody who has prediabetes has metabolic syndrome.


Metformin, an inexpensive drug sold under various brand names,* is often used to stave off the onset of type 2 diabetes by helping people with prediabetes control the amount of glucose in their bloodstream. Originally discovered in the 1920s, metformin was neglected for years as researchers focused on insulin as a means of managing diabetes. Now, healthcare professionals like the drug because it rarely produces hypoglycemia, the state in which blood sugar can drop to dangerously low levels. The drug, officially designated N,N-dimethylimidodicarbonimidic diamide, belongs to the biguanide class of drugs.

* Fortamet, Glucophage, Glucophage XR, Glumetza, Riomet


“Milligrams per deciliter” is the common unit of measurement of glucose in the bloodstream. Healthcare workers use this number, taken after a fast, to determine whether a person is normal, pre-diabetic, or diabetic.

Normal = A pre-meal “fasting” range from 70 mg/dL to high 90s mg/dL. Until recently, “normal” extended up to and past 100 mg/dL. But it is now thought that fasting readings in the 90s and low 100s are indicators of prediabetes.

Prediabetic =  low 100s. Currently, many healthcare providers are beginning to flag people whose mg/dL readings are in the low 100s and consider them as having prediabetes. The diagnosis can help patients with prediabetes begin the making the lifestyle changes that can delay or deny the onset of type 2. 

Diabetic = A fasting blood sugar measurement of 126 mg/dL or greater, as defined by the American Diabetes Association. Although people with diabetes can lower their fasting levels to below 100 mg/dL, they do so through a conscientiously applied combination of diet, exercise, and medicine that can control, but not cure, the disease. 


The condition in which a person is heading toward acquiring type 2 diabetes unless he or she takes steps to avoid its onset. Typical ways of avoiding type 2 include regular exercise, weight control (fewer calories and carbohydrates), and sometimes drugs, such as metformin, to control blood sugar levels.

Among conditions that can indicate prediabetes are:

  •  An A1C reading of 5.7% to 6.4%
  •  High blood pressure
  •  High cholesterol
  •  Overweight (a BMI of 25+)
  •  A sedentary lifestyle
  •  Age over 45 years
  •  A family history of diabetes

Membership in an ethnic group that has higher proportions of people with type 2 diabetes: Native American, African American, Hispanic, East Asian, South Asian, Pacific Islander


A common long-term side effect of diabetes, retinopathy involves the gradual destruction of the small blood vessels that supply the retina in the eye. Inflammation brought on by too much glucose in the bloodstream eventually weakens the walls of the vessels and makes them leak. Attempts by the body to heal the leakage create replacement tissue that is weak and thin, as well as scarring. Retinopathy causes a loss of visual sharpness and in its most extreme form, because of extensive damage to the retina, can cause blindness.

Type 1 diabetes

An autoimmune disease, believed to have a genetic basis, in which the body attacks and destroys the pancreatic cells that produce insulin. Previously called “juvenile diabetes” because it is most likely to appear when a person is young, the disease requires close monitoring of blood sugar and the self-administration of insulin to keep blood sugar at healthy levels.

About 10 percent of people who suffer from diabetes have type 1.

While there is no cure for type 1, scientists are preparing to battle the disease through several promising experimental approaches:

  •  Transplanting insulin-producing cells from pigs to humans. (There has been some success with this experimental procedure, with pig cell recipients experiencing up to two years free of symptoms or the need to self-dose with insulin. The drawback is the eventual rejection of the cells by the body’s autoimmune response.)
  •  The “artificial pancreas,” a combination of a blood glucose monitor and an insulin reservoir/pump that is attached to a person’s body. The monitor automatically checks blood sugar levels continuously, and a computer sends commands to the pump to dose the wearer with insulin in response to the monitor’s readings.
  •  Oral doses that bypass the inconvenience and pain of needle-injected insulin. The trick is to deliver insulin to the small intestine intact, without having its delicate structure damaged or destroyed by digestive juices. One experimental approach is to “wrap” insulin in a saliva and stomach-acid resistant carrier like vitamin B12, which can then carry the insulin safely to the point where it can be delivered to the bloodstream.
  •  Altering genetic commands. For example, directing T-cells that attack the pancreas’s insulin-producing cells to stop doing so by giving them a new set of instructions.

Type 2 diabetes

Previously called “adult onset diabetes,” type 2 affects about 90 percent of all people who have diabetes. In this form of diabetes, the body gradually loses its ability to properly use insulin (insulin resistance) or produce enough insulin (insulin deficiency). Eventually the body loses any ability to adequately control blood sugar levels.

The disease is treated with a combination of healthy eating, exercise, and medication. Newly diagnosed type 2s routinely start on such medications as metformin or sulfonylureas, which are designed to lower the level of glucose in the blood or help the body use what insulin it produces. Because the disease is “progressive,” it advances through different stages, depending on the individual. In later stages, insulin may become necessary to control blood sugar levels.

Although people who develop type 2 may be genetically predisposed to it, the disease is not an autoimmune disease like type 1. Because of this, it is possible for people who are at risk for type 2 to take steps to delay or even completely block its onset. For people who have prediabetes, the best way to avoid getting type 2 is to act as though they already have it, by making the same lifestyle changes that type 2s make to manage their disease.

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