"Diabetes
mellitus," more commonly referred to as "diabetes," is a
condition that causes blood sugar to rise to dangerous levels: a fasting blood
glucose of 126 milligrams per deciliter (mg/dL) or more.
How Diabetes Develops
Most of the food you eat
is turned into glucose, or sugar, for your body to use for energy. The
pancreas, an organ near the stomach, produces a hormone called insulin. This
hormone is necessary for the body to be able to use sugar or glucose, the basic
fuel for cells in the body. Insulin's role is to take sugar from the blood into
the cells. When your body does not produce enough insulin and/or does not
efficiently use the insulin it produces, sugar levels rise and build up in the
bloodstream. When this happens, it can cause two problems:
1. Right away, the body's
cells may be starved for energy.
2. Over time, high blood
glucose levels may damage the eyes, kidneys, nerves or heart.
Types of Diabetes
There are two main types
of diabetes: type 1 diabetes and type 2 diabetes. Both types may be inherited
in genes, so a family history of diabetes can significantly increase a person's
risk of developing the condition.
Type 1 diabetes is a serious condition that occurs when the pancreas
makes little or no insulin. Without insulin, the body is unable to take the
glucose (blood sugar) it gets from food into cells to fuel the body. So without
daily injections of insulin, people with type 1 diabetes won't survive. For
that reason, this type of diabetes is also referred to as insulin-dependent diabetes.
Type 1 diabetes was previously known as juvenile diabetes because it's usually
diagnosed in children and young adults. However, this chronic, lifelong disease
can strike at any age, and those with a family history of it are particularly
at risk.
Health
Risks for Type 1 Diabetes
During the development of type 1 diabetes, the body's immune system attacks
certain cells (called beta cells) in the pancreas. Although the reasons this
occurs are still unknown, the effects are clear. Once these cells are destroyed,
the pancreas produces little or no insulin, so the glucose stays in the blood.
When there's too much glucose in the blood, especially for prolonged periods,
all the organ systems in the body suffer long-term damage. Learn more about the health consequences of diabetes and how to treat it.
Type
2 diabetes is the most common form of diabetes. Historically, type 2 diabetes
has been diagnosed primarily in middle-aged adults. Today, however, adolescents
and young adults are developing type 2 diabetes at an alarming rate. This
correlates with the increasing incidence of obesity and physical inactivity in
this population, both of which are risk factors for type 2 diabetes.
This type of diabetes can occur when:
- The body
develops "insulin resistance" and can't make efficient use of
the insulin it makes, and
- The pancreas
gradually loses its capacity to produce insulin.
In a mild form, this type
of diabetes can go undiagnosed for many years, which is a cause for great
concern since untreated diabetes can lead to many serious
medical problems, including cardiovascular disease. Type 2 diabetes may be delayed
or controlled with diet and exercise.
Precursors to Diabetes
In addition to
full-blown diabetes mellitus, there are precursors to the disease:
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Prediabetes
is a condition in which fasting blood glucose (blood sugar) levels are higher
than normal but have not quite reached the 126 milligrams/deciliter (mg/dL)
threshold considered to be full-blown diabetes.
Any of the following blood test results identify prediabetes:
- Impaired fasting glucose
(IFG): A person is considered to have IFG with a fasting blood glucose
ranging from 100 to 125 mg/dL.
- Impaired glucose
tolerance (IGT): Individuals with IGT have a fasting glucose less than 126
mg/dL and a glucose level between 140 and 199 mg/dL two hours after
taking an oral glucose tolerance test.
- Higher than normal A1C: A
person is considered to have an abnormal A1C level between 5.7-6.4%. The
A1C test measures your average blood glucose control for the past 2 to 3
months.
Health
Risks for Prediabetics
The American Heart Association estimates that 81.5 million Americans 20
years and older have prediabetes. People with IFG and IGT are at increased risk
for developing type 2 diabetes, heart disease and stroke. Long-term damage to
the cardiovascular system may occur while a person has prediabetes, and a
recent study indicates that prediabetes more than doubles the risk of death due
to heart attack.*
* Circulation,
July 10 2007; doi:10.1161/CIRCULATIONAHA.106.685628
Insulin resistance
Both type 2 diabetes and
prediabetes usually result from insulin resistance.
Insulin resistance, which is a condition that affects more than 60 million
Americans, occurs when the body can't use insulin efficiently. To compensate,
the pancreas releases more and more insulin to try to keep blood sugar levels
normal. Gradually, the insulin-producing cells in the pancreas become defective
and ultimately decrease in total number. As a result, blood sugar levels begin
to rise, causing prediabetes and, eventually, type 2 diabetes to develop.
When a fasting individual has too much glucose in the blood (hyperglycemia) or
too much insulin in the blood (hyperinsulinemia), it indicates a person may
have insulin resistance.
Health Risks of Insulin
Resistance
This content was last reviewed on 6/28/2012.