What is diabetes?
When you eat, some of your food is broken down into sugar
(also called glucose). Sugar travels in your blood to all your
body’s cells. Insulin helps sugar move from your blood into
your cells. Insulin is a hormone that is made by the beta cells
in your pancreas.
Your cells need sugar for energy. Sugar from food makes your blood sugar level go
up. Insulin lowers your blood sugar level by helping sugar move from your blood
into your cells.
When you eat, another hormone made in the gut helps the pancreas produce the
right amount of insulin to move sugar from the blood into the cells. This hormone is
called GLP-1. It stimulates the beta cells in the pancreas to produce insulin when
the blood sugar is too high. It also helps to lower the amount of sugar made by the
liver.
There is also a third hormone called glucagon that tells the liver to release stored
sugar if your blood sugar gets too low or if you have not eaten for many hours,
such as overnight.
What happens in diabetes?
When you have diabetes:

Your pancreas does not make any insulin, or

It does not make enough insulin (and over time will make less and less), or

Your body prevents the insulin you do make from working right
As a result, sugar can’t get into your cells. So it stays in your blood. That’s why
your blood sugar gets too high (also called hyperglycemia). There are three ways to
diagnose diabetes:
1. When the fasting blood sugar level is 126 mg/dL or higher. Fasting blood
sugar levels means no food for at least eight hours prior to checking your
blood sugar.
2. When symptoms of high blood sugar are present and a blood test taken at a
random time shows a blood sugar level of 200 mg/dL or higher.
3. When the results of another test, called a glucose tolerance test (GTT), are
200 mg/dL or higher. On the day of the test, you will be asked to drink a
sugary liquid on an empty stomach. Your blood will then be tested several
times over the next few hours to see how well your body handles the sugar in
your blood.
Following your diabetes care plan helps keep your sugar and insulin in balance, the
way your body did before diabetes.
Blood sugar goals
Keeping your blood sugar levels as close to the normal range as possible may help
reduce your risk of diabetes-related health problems. Diabetes experts recommend
that people with diabetes keep their blood sugar levels between 70 and 130 mg/dL
before meals and less than 180 mg/dL one to two hours after meals.
You and your diabetes care team set your blood sugar goals based on your diabetes
care plan.
“Having diabetes has been a little like learning to drive a
car. At first it seemed like there was so much to remember,
but pretty soon it got a lot easier. Just like driving, diabetes
keeps me on my toes because there is plenty to watch out for.
But now it's second nature, and not all that hard.”
— WF, age 61
The types of diabetes
The most common types of diabetes are type 1 and type 2.
What is type 1 diabetes?
In type 1 diabetes, the body does not make insulin. Insulin must be injected into
the body. Type 1 diabetes occurs more often in children and young adults than in
older adults.
What is type 2 diabetes?
In type 2 diabetes, your body prevents the insulin it does make from working right.
Your body may make some insulin, but not enough. Most people with diabetes have
type 2. Many are adults older than age 40 years. But the number of children and
young adults with type 2 diabetes is rising, mainly because of obesity.
Type 2 diabetes is progressive
All people with type 1 diabetes need to take insulin. Diabetes experts advise that
most people with type 2 diabetes need medicines to manage their blood sugar. As
type 2 diabetes changes, different types of medicine are usually necessary to
manage blood sugar. This is because over time, the beta cells in the pancreas
produce less and less insulin. Your diabetes care team will help you develop a
diabetes care plan that is right for you.
Expert advice on diabetes

What Is Diabetes?
(Approx 4.5 min)
Explanation of what happens in diabetes
Play Video

What Is Type 1 Diabetes?
(Approx 7 min)
Explanation of type 1 diabetes
Play Video

What Is Type 2 Diabetes?
(Approx 4 min)
Explanation of type 2 diabetes
Play Video
Other kinds of diabetes
Gestational diabetes
Gestational diabetes is high blood sugar that develops during pregnancy. Blood
sugar levels usually return to normal after the baby is born. However, about half of
women who have gestational diabetes will develop type 2 diabetes later in life.
Managing your weight and getting regular physical activity can reduce the risk of
getting type 2 diabetes.
Diabetes can be caused by other illnesses
Certain kinds of medicine can also affect blood sugar levels. Be sure to tell your
doctor about all the medicines you take, as well as any vitamins, minerals, and
herbs. Your doctor can tell you if anything you are taking could cause a rise in blood
sugar.
Prediabetes
Prediabetes is when your blood sugar levels are above normal but not high enough
for a diagnosis of diabetes. A normal fasting blood sugar level is below 100 mg/dL.
Prediabetes is when the fasting blood sugar level is between 100 and 125 mg/dL or
the results of the glucose tolerance test (GTT) are between 140 and 199 mg/dL.
It's estimated that about 57 million people in the United States have prediabetes.
Like diabetes, prediabetes can lead to damage to the heart and blood vessels. The
good news is that with changes in their meal plan and physical activity, people with
prediabetes may reduce their risk of developing type 2 diabetes. Experts
recommend that people with prediabetes reduce their weight by 5% to 10% and
get at least 30 minutes of physical activity 5 days a week.