American Medical Association Family Medical Guide - American Medical Association [603]
Glucose is found in many foods, including some that don’t taste sweet. Glucose is the major source of energy for all the cells in the body. Insulin stimulates cells in the body to absorb glucose from the blood for the energy they need, and insulin stimulates the liver to absorb and store the glucose that isn’t used. In this way, insulin maintains glucose at a healthy level in the blood. Glucagon does the opposite—it helps raise the glucose level in the blood by stimulating the liver to release glucose (hypoglycemia; see page 897). Too much glucose in the blood can cause diabetes (see next page) and can damage organs and tissues throughout the body.
The pancreas
The pancreas is a hormone-secreting gland about 6 to 8 inches long that lies close to the duodenum (the upper part of the small intestine that opens into the stomach) and is linked to the duodenum by the pancreatic duct. The pancreas secretes enzymes that aid digestion, and several hormones, including insulin (which helps the body use and store the sugar glucose).
Type 1 Diabetes
Type 1 diabetes, which used to be called juvenile or insulin-dependent diabetes, occurs when the pancreas stops producing the hormone insulin or does not produce the hormone in the amounts the body needs. The lack of insulin prevents cells from bringing in the sugar glucose for energy and prevents the liver from absorbing and storing glucose. If glucose cannot be used or stored, it builds up in the blood and spills over into the urine. An abnormally high level of glucose in the blood is the hallmark of diabetes.
In type 1 diabetes, insulin-producing cells in the pancreas (islet cells) produce very little or no insulin. Type 1 diabetes occurs mainly in young people, but can occur at any age. About 5 to 10 percent of the 17 million people in the United States with diabetes have type 1 diabetes. In most cases, type 1 diabetes results from an errant immune response in which the immune system mistakes the islet cells of the pancreas for invading organisms and attacks them, damaging or destroying them. Type 1 diabetes can also develop in people who have chronic diseases that can damage the insulin-secreting cells in the pancreas, such as cystic fibrosis (see page 958) or long-term alcohol abuse (see page 733).
Unable to use glucose for energy because of the lack of insulin, the body is forced to obtain energy from fat. As fat is burned, chemicals called ketones and keto acids are produced. A buildup of these substances is a life-threatening condition called ketoacidosis, characterized by dehydration and very high levels of glucose in the blood.
Over time, uncontrolled high blood levels of glucose can cause serious complications, including the eye disorder diabetic retinopathy (see page 1048), which can lead to blindness; peripheral neuropathy (see page 702) and other nerve diseases; and chronic kidney failure (see page 817). People with diabetes have a higher-than-average risk of developing atherosclerosis (see page 557), a major risk factor for stroke, heart attack, and high blood pressure. For people with diabetes, treatment of high blood pressure and elevated cholesterol is just as important as controlling glucose levels in avoiding heart disease and some of the other possible complications of diabetes. People with diabetes also have an increased risk of developing infections.
If you have diabetes, always tell your doctors or dentists before you have any treatments, so they can take any necessary precautions. Your doctor can give you a card to carry at all times that lists your name, address, the fact that you have diabetes, and instructions on how to help you if you become ill. Wear a medical identification bracelet or necklace indicating that