Diabetes Basics

What is Diabetes?

Diabetes is a disease resulting from an inability to use and/or produce insulin, a hormone made by the pancreas. Insulin helps get glucose, a form of sugar from foods we eat, into our body cells to burn for energy. After eating, blood glucose levels rise and insulin is produced to help get glucose into cells. If the body cannot produce insulin (type 1 diabetes) or cannot use it properly (type 2 diabetes), blood glucose levels build up in the blood. Diabetes is diagnosed based on elevated blood glucose levels.

Types of Diabetes

Type 1 Diabetes

Type 1 diabetes is an autoimmune disease which occurs primarily in children and young adults under the age of 40. However, disease onset can occur at any age. An autoimmune disease occurs when the immune system turns against a part of the body. In diabetes, the immune system attacks and destroys the islet cells which produce insulin in the pancreas. The pancreas then produces little or no insulin. A person who has type 1 diabetes must take insulin daily. Although the cause of type 1 diabetes is unknown, there are three factors which play a part in determining why a person develops diabetes:

  • Genetic or inherited factors
  • Self-allergy
  • Environmental damage

Type I diabetes accounts for 5-10 percent of those diagnosed with diabetes in the United States.

Symptoms of type 1 diabetes include:

  • Frequent thirst and urination
  • Constant hunger
  • Weight loss
  • Blurred vision
  • Extreme fatigue
  • Wetting the bed in children who were dry through the night

Populations most at risk for developing type 1 diabetes include those of Northern European ancestry.

To learn more about type 1 diabetes, visit the CDC's website on the suject.

Type 2 Diabetes

The most common form of diabetes is type 2 diabetes. 90-95 percent of people diagnosed with diabetes have type 2 diabetes. Type 2 diabetes is most often associated with genetics and lifestyle, and has even been nicknamed a “disease of lifestyles.”

In type 2 diabetes, there is a problem with the action of insulin. The pancreas becomes insulin resistant. This usually occurs with excess weight and physical inactivity. Type 2 diabetes has a higher inheritance risk than type 1 diabetes.

Common factors that are associated with type 2 diabetes include:

  • Obesity
  • Family history of diabetes
  • Previous diagnosis of gestational diabetes
  • Physical inactivity
  • Race/ ethnicity
  • Age (> 40 years)

Type 2 diabetes is increasingly being diagnosed in children and adolescents, and if current trends continue, one in three children will develop type 2 diabetes in their lifetime. Populations most at risk for developing type 2 diabetes are Native Americans, African Americans, and Latinos.

To learn more about type 2 diabetes, visit the CDC's website on the subject.

Gestational Diabetes

Some women develop gestational diabetes late in pregnancy. Although this form of diabetes usually disappears after the birth of the baby, women who have had gestational diabetes have a 20 to 50 percent chance of developing type 2 diabetes within 5 to 10 years. Maintaining a reasonable body weight and being physically active may help prevent the development of type 2 diabetes.

Three to eight percent of pregnant women in the United States develop gestational diabetes. As with type 2 diabetes, gestational diabetes occurs more often in some ethnic groups and among women with a family history of diabetes. Gestational diabetes is caused by the hormones of pregnancy or a shortage of insulin. Women with gestational diabetes may not experience any symptoms.


Pre-diabetes is a term used to distinguish people who have higher than normal blood glucose levels, but not high enough to be classified as diabetes. Progression to diabetes among those with pre-diabetes is not inevitable. Studies suggest weight loss (even just 5%) and increased physical activity among people with pre-diabetes prevents or delays diabetes and may return blood glucose levels to normal.

If you are overweight, physically inactive, and have a family history of diabetes, you may be at risk for developing type 2 diabetes.

To learn more about pre-diabetes and to see if you may be at risk for developing diabetes, visit this site.

Diagnosing Diabetes

How Do I Know if I Have Diabetes?

Warning signs for diabetes can vary, so anyone at risk for diabetes should consult with their physician even if these symptoms are not present. Those at risk include:

  • Anyone with a family history of diabetes
  • Persons who are overweight
  • Individuals over the age of 40
  • People who are not very active
  • Women who gave birth to a baby weighing over 9 lbs
  • Individuals of African American, Hispanic/Latino, Asian American/Pacific Islander ancestry

If these signs and symptoms are present, contact your physician immediately. Symptoms include:

  • Extreme thirst
  • Frequent urination
  • Numb/tingling feet
  • Blurry vision
  • Fatigue
  • Unexplained weight loss
  • Sores which do not heal

Tests Used to Diagnose Diabetes

Several tests are used to diagnose diabetes and must all be completed or confirmed by a doctor or health practitioner.

Fasting Plasma Glucose Test (FPG): The Fasting Plasma Glucose test measures blood glucose in a person who has fasted – has had no food or drink except water – for at least eight hours. The FPG test is usually done first thing in the morning and is used to detect both diabetes and pre-diabetes.

  • A fasting glucose level of 100 to 125 mg/dL indicates impaired fasting glucose (IFG), a form of pre-diabetes.
  • A level of 126 mg/dL or above indicates diabetes. (Results must be confirmed by a second test).

The Oral Glucose Tolerance Test (OGTT): During the OGTT, blood glucose levels are checked before and after 75 grams of glucose dissolved in water are consumed. Patients also typically fast for eight hours preceding the test. The OGTT is used to diagnose diabetes, pre-diabetes and gestational diabetes. The OGTT is more sensitive than the FPG test but may be less convenient to administer. To test for diabetes or pre-diabetes using the OGTT:

  • A blood glucose level between 140 and 199 mg/dL two hours later indicates a type of pre-diabetes called impaired glucose tolerance (IGT).
  • A blood glucose level of 200 mg/dL or above after two hours and confirmed by a second two-hour test, indicates diabetes.

A1C Test: Red blood cells encode your blood sugar when they are born and live 3 months. Thus the A1C test is a blood test which reflects average blood glucose levels over the preceding three months. An A1C test is more convenient for patients than traditional glucose tests, as it does not require fasting and can be performed any time of day.

  • A normal A1C level is below 5.7%.
  • An A1C of 5.7% to 6.4% generally indicates pre-diabetes.
  • A level of 6.5% or above indicates diabetes.

The A1C is not for everyone. The A1C is not recommended for use in diagnosing gestational diabetes or type 1 diabetes.

Those of African, Mediterranean, or Southeast Asian descent or individuals who have family member with sickle cell anemia or a thalassemia are particularly at risk of interference.

False A1C test results may also occur in individuals with other illnesses which affect their blood or hemoglobin such as chronic kidney disease, liver disease, or anemia.

Random or Casual Blood Test: The random or casual blood test is performed any time of day, and is especially helpful if you have symptoms of diabetes such as extreme thirst, frequent urination, blurred vision or fatigue. Blood glucose readings of 200 mg/dL or greater indicate diabetes.

Is There a Cure?

While there is no cure for diabetes, it can be managed by healthy eating, physical activity, and medication. Learning how to keep blood glucose levels close to a normal range will result in fewer complications. Adults and children with diabetes should see a health care provider in order to learn how to manage their diabetes. Having a team of providers such as internists, family practice doctors, or pediatricians can improve diabetes care.