II.

Type 1 Diabetes

Diabetes is classified into two types. In Type 1 diabetes, formerly called insulin-dependent diabetes mellitus (IDDM) and juvenile-onset diabetes, the body does not produce insulin or produces it only in very small quantities. Symptoms usually appear suddenly, typically in individuals under 20 years of age. Most cases occur around puberty—around age 10 to 12 in girls and age 12 to 14 in boys. In the United States Type 1 diabetes accounts for 5 to 10 percent of all diabetes cases. In Canada, Type 1 diabetes accounts for about 10 percent of all diabetes cases.

Type 1 diabetes is a disease in which the body produces too little insulin or no insulin at all. In most cases, Type 1 diabetes is an autoimmune disease, that is, a condition in which the body’s disease-fighting immune system goes awry and attacks healthy tissues. In the case of Type 1 diabetes, the immune system mistakenly attacks and destroys insulin-producing cells, known as beta cells, in the pancreas. Scientists believe that a combination of genetic and environmental factors somehow triggers the immune system to destroy these cells. Scientists have so far identified 20 genes that play a role in Type 1 diabetes, although the exact function of these genes is still under investigation. Environmental factors, such as certain viruses, may also contribute to the development of the disease, particularly in people who already have a genetic predisposition for the disease. Type 1 diabetes also can result from surgical removal of the pancreas.

In addition to causing a buildup of glucose in the blood, untreated Type 1 diabetes affects the metabolism of fat. Because the body cannot convert glucose into energy, it begins to break down stored fat for fuel. This produces increasing amounts of acidic compounds in the blood called ketone bodies, which interfere with cellular respiration, the energy-producing process in cells.