Diabetes (Type 1), Part 1 — Introduction, Incidence, Symptoms and Complications

What is Type 1 diabetes?

Type 1 diabetes is also known as "insulin-dependent diabetes mellitus" (IDDM) or "juvenile-onset diabetes mellitus". Although type 1 diabetes can appear at any age, most often it is diagnosed prior to the age of 30, as opposed to type 2 diabetes, which is most commonly diagnosed in adulthood. In type 1 diabetes, the onset of symptoms is usually rapid and severe. Control of type 1 diabetes is achieved by the use of insulin injections for the rest of the person's life. The exact cause is not known, and there is no cure for it.

Normally, the beta cells (located in the head of the pancreas) secrete insulin, which helps the body metabolize the glucose (sugar) in the blood. Type 1 diabetes occurs when the pancreas does not produce enough insulin to regulate blood sugar levels appropriately. Without adequate insulin,

  1. glucose is not used by the cells but instead builds up in the bloodstream, leading to very elevated glucose levels
  2. despite the high levels of glucose, the body is unable to use the glucose for energy, resulting in increased hunger
  3. the elevated glucose levels also cause the kidneys to produce large volumes of urine, which results in increased thirst

While the early course of diabetes is characterized by insufficient levels on insulin, within about five years of diagnosis, the insulin-producing beta cells are completely destroyed, and produce no insulin at all.

Incidence and prevalence

Diabetes peaks in adolescence.

Overall incidence is approximately 15 cases per 100,000 individuals annually, and increasing. About three children out of 1,000 will develop type 1 diabetes by age 20. Whites seem to be affected more often than blacks, who have the lowest overall incidence of type 1 diabetes among major ethnic groups. Male-to-female ratio is split evenly. Diagnosis of type 1 diabetes can occur throughout childhood up to age 30, but the peak incidence lies in adolescence. Type 1 diabetes rarely develops in older adults, but is increasingly being recognized through the measurement of islet-cell antibodies.

Type 2 diabetes is generally associated with increased weight and more sedentary lifestyles among adults. There is growing concern among healthcare providers about an observed increase in type 2 diabetes among children and adolescents.

"If you go back 20 years, about two percent of all cases of new onset diabetes (type 2) were in people between 9 and 19 years old. Now, it's about 30 to 50 percent", noted Dr. Gerald Bernstein, a past president of the American Diabetes Association (ADA) and an endocrinologist with Beth Israel Medical Center in New York City.

Health experts blame the trend on burgeoning rates of obesity among children and adolescents during the past three decades. Indeed, the emerging epidemic of type 2 diabetes among children reflects a trend in the entire population. In August 2000, the Centers for Disease Control and Prevention (CDC) issued a report examining the incidence of type 2 diabetes among 30- to 39-year-old adults, and found that the rate had increased 70 percent during the period 1990 to 1998. Over the same period, the rates of the disease rose 40 percent among those aged 40 to 49, and 31 percent among those aged 50 to 59, according to the same report. As the prevalence of obesity and limited exercise increases among children and adolescents, it is anticipated that the rate of type 2 diabetes will increase in these populations as well.

For more information about type 1 and type 2 diabetes in children, please visit:


Symptoms of type 1 diabetes

The sudden onset and severity of symptoms of type 1 diabetes usually require prompt medical attention. Symptoms include:

  • increased thirst
  • increased urination
  • weight loss, despite increased appetite
  • nausea
  • vomiting
  • abdominal pain
  • fatigue
  • absence of menstruation
  • double vision


Besides the symptoms listed above, more serious symptoms can be seen, particularly if the diabetes is not kept under control. These complications can constitute emergencies, and require immediate medical attention.

Diabetic ketoacidosis

Complicatioons of diabetes can be serious.

This complication occurs when the body lacks insulin and must burn fat as an energy source. Burning fat is not terribly efficient, and produces byproducts called ketones. Ketones accumulate in the blood, and make it acidic. The ketones also spill over into the urine, exacerbating the patient's need for fluids. The lack of glucose for the cells, plus the ketones and acidity, create an environment that makes normal brain function difficult.


Proper management of diabetes requires a careful balance between activity, diet and insulin injections. Hypoglycemia (low blood sugar) occurs when this balance is lost.

In the mild forms of hypoglycemia, the person may experience hunger, nervousness, and an increased heart rate. If the hypoglycemia becomes more severe, confusion and loss of consciousness might result. If not treated quickly, hypoglycemia can even lead to a coma.

Long-term complications

In addition to the immediate concerns about hypoglycemia and ketoacidosis, long-term complications of diabetes need close attention and prevention. These are generally seen in people who have had diabetes for many years. Good management of diabetes can help minimize these long-term complications:

  • vascular disease
  • microvascular disease
  • eye complications
  • diabetic nephropathy (kidney disease)
  • diabetic neuropathy (nerve disease)
  • foot problems
  • skin and mucus membrane problems

For more information, see:

Part 2 — Treatment and Monitoring

Part 3 — Education, Restrictions, and Implications for School

American Diabetes Association

ATTN: National Call Center
1701 North Beauregard Street
Alexandria, VA 22311

Contributed by:

Kathy Davis, MSEd, PhD
Associate Professor
Project Director, Connected Kansas Kids
Director, KU Kids Healing Place
University of Kansas Medical Center