Type 1 Diabetes

Basics

Type 1 diabetes is a disorder characterized by high levels of sugar (glucose) in the blood. Diabetes consists of two forms: type 1, previously called "juvenile-onset" diabetes, and type 2, previously called "adult-onset" diabetes. Type 1 diabetes usually starts suddenly before age 30, and usually in children before age 13, but may occur at any age. Type 2 diabetes, conversely, tends to affect adults above the age of 30, but also may affect children and young adults. Type 1 diabetes accounts for 10% of cases of diabetes. It requires daily insulin injections because the body loses its ability to manufacture any insulin, the hormone that regulates blood sugar. Type 2 diabetes, on the other hand, is caused by a combination of insulin resistance and an inability of the cells of the pancreas to produce enough insulin.

Over time, high blood sugar levels can damage blood vessels and nerves, and lead to serious health problems. Some of the problems that can be caused by uncontrolled diabetes include:

• blindness
• kidney failure
• heart attack
• stroke

Causes

In type 1 diabetes, the body does not produce enough insulin, the hormone that regulates blood sugar [Figure 1]. Insulin is secreted by the pancreas (a pear-shaped organ near the stomach) to maintain proper blood sugar levels, which should range anywhere from 60 mg/dL to 110 mg/dL. Blood sugar (glucose) is the fuel the body needs to perform every function. Carbohydrates from food are broken down into this simple sugar, which the body uses for immediate energy needs, or else stores (as glycogen) for future use.

Figure 1. Cellular mechanisms of diabetes (animation and audio)

After a meal, blood sugar rises, and a healthy pancreas secretes insulin into the bloodstream. Insulin acts like a lock and key, and opens the door for cells to use glucose. As blood sugar falls, a healthy pancreas scales back insulin production accordingly to maintain the blood sugar in the normal range. In people with type 1 diabetes, this process is disrupted. For unknown reasons, the body’s immune system turns on and attacks the cells in the pancreas that make insulin (beta cells). This faulty immune response obliterates beta cells and shuts down insulin production. Consequently, blood sugar levels can become dangerously high.