What Is Prediabetes?

People with prediabetes have glucose levels that are higher than normal but not high enough yet to indicate diabetes. The condition used to be called borderline diabetes. Most people with prediabetes don't have symptoms, but they are considered to be at high risk of developing heart disease.

Normally, your body produces a hormone called insulin to help your cells use the energy (glucose) found in food. With diabetes, either your body doesn't make enough insulin or doesn't efficiently use the insulin it does produce. When glucose builds up in the blood, it can damage the tiny blood vessels in the kidneys, heart, eyes, and nervous system.

With prediabetes, the subtle balance between glucose and insulin has been thrown off. The pancreas may not be able to produce enough insulin after a meal to "clear" the incoming glucose from the blood. Or cells may be insulin resistant. When cells are insulin resistant, they won't allow the insulin to escort glucose from the bloodstream into them. Too much glucose in the blood is also called high blood sugar or hyperglycemia. A low blood sugar level is called hypoglycemia.

If you have prediabetes, you're at high risk of developing type 2 diabetes as well as the serious medical problems associated with diabetes, including heart disease  and stroke. With prediabetes, you are at a 50% higher risk of heart disease and stroke than someone who does not have prediabetes.

Source: http://diabetes.webmd.com/guide/what-is-prediabetes-or-borderline-diabetes

What is Diabetes?

Too Much Glucose in the Blood

Diabetes, often referred to by doctors as diabetes mellitus, describes a group of metabolic diseases in which the person has high blood glucose (blood sugar), either because insulin production is inadequate, or because the body's cells do not respond properly to insulin, or both. Patients with high blood sugar will typically experience polyuria (frequent urination), they will become increasingly thirsty (polydipsia) and hungry (polyphagia).

Diabetes means your blood glucose (often called blood sugar) is too high. Your blood always has some glucose in it because your body needs glucose for energy to keep you going. But too much glucose in the blood isn't good for your health.

Glucose comes from the food you eat and is also made in your liver and muscles. Your blood carries the glucose to all of the cells in your body. Insulin is a chemical (a hormone) made by the pancreas. The pancreas releases insulin into the blood. Insulin helps the glucose from food get into your cells.

If your body does not make enough insulin or if the insulin doesn't work the way it should, glucose can't get into your cells. It stays in your blood instead. Your blood glucose level then gets too high, causing pre-diabetes or diabetes.

Source: http://nihseniorhealth.gov/diabetes/diabetesdefined/01.html