Diabetes is considered a complex group of diseases with a variety of causes. It is also often called a syndrome, or a combination of associated conditions. In most cases, people with diabetes have a high amount of glucose (a sugar) in their blood, also referred to as high blood glucose (or sugar) levels or, in Diabetes is considered a complex group of diseases with a variety of causes. It is also often called a syndrome, or a combination of associated conditions. In most cases, people with diabetes have a high amount of glucose (a sugar) in their blood, also referred to as high blood glucose (or sugar) levels or, in the case of extremely high glucose levels, hyperglycemia. It is a disease that occurs when for various reasons the body’s cells are unable to absorb excess glucose from the blood, which causes an overabundance of the sugar in the body. This is a very basic definition, as there are several types of diabetes, including type 1, type 2, and gestational diabetes.
For simplicity, and because most media mentions that diabetes is a disease (after all, it does include a collection of diseases with various causes), the remainder of this text will mention diabetes as a “disease” not a “syndrome.”
What is the medical term for the condition caused by the body’s inability to produce or use insulin?
Diabetes mellitus is the medical term for the disease associated with the body’s inability to naturally produce or use insulin. There are two major types—one is considered an autoimmune disease (type 1), and the other is a disorder of the body’s metabolism, or the way the body processes food for energy (type 2). In general, diabetes occurs when the pancreas either produces little or no insulin, or when the cells do not respond appropriately to the insulin that is produced. Because of either of these conditions, glucose (sugar) builds up in the bloodstream (causing high blood glucose levels) and overflows into the urine. This excess amount of glucose is why a health care professional will tell patients newly diagnosed with diabetes that they have “high blood glucose levels.”
What is insulin?
Insulin is a hormone produced by the beta cells in the pancreas, an approximately six-inch-long organ found behind the stomach and below the liver. After a meal is eaten, insulin is released from the pancreas in response to rising blood glucose levels (most foods cause a person’s blood glucose level to rise). The insulin then helps the passage of the glucose, along with amino acids and fatty acids, into the body’s cells, which helps facilitate storage for future energy needs and cellular growth. (For more about insulin and the pancreas, see the chapter “How Diabetes Affects the Endocrine System”; for more details about insulin, see the chapter “Taking Charge of Diabetes.”)
What is insulin resistance?
Insulin resistance is a condition most associated with type 2 diabetes. It occurs when the body’s natural hormone insulin is less effective in reducing a person’s blood glucose levels. This is caused by the body’s cells being resistant to insulin’s action, and/or not enough insulin is made in the pancreas. Either situation makes the glucose levels rise and, if severe enough, can lead to type 2 diabetes and other health problems. (For more about insulin resistance, see the chapter “Prediabetes and Type 2 Diabetes.”)
What is glucose?
During digestion, the fats, carbohydrates, and proteins consumed are eventually broken down into smaller components that can be used by the body’s cells. One of the components is glucose, a six-carbon sugar that is a fuel providing energy the body’s cells need. It is the imbalance of this glucose in the body—mainly too much glucose—that can lead to diabetes. (For more about glucose and the digestive tract, see the chapter “How Diabetes Affects the Digestive System.”)
What is the difference between “sugar” and “glucose” in discussing diabetes?
The terms “sugar” and “glucose” are often used interchangeably in relation to diabetes. Both terms are actually correct, as glucose is a form of sugar. But the term “sugar” is more commonly used by the public, which is why many people will say they “have sugar” when they are diagnosed with any type of diabetes.
What is glucagon?
Glucagon is a hormone produced by the pancreas’s alpha cells. This hormone is responsible for increasing the concentration of glucose in the blood. It is secreted from the pancreas when the blood glucose levels fall below normal. Glucagon actually stimulates the liver to convert glycogen to glucose, which causes the person’s blood glucose level to rise. It does this by stimulating the production of glucose from amino acids and lactic acid in the liver and stimulates the release of fatty acids from fat (also called adipose) tissues. And when blood glucose levels sufficiently rise in the blood, the secretion of glucagon decreases as part of what is called a negative feedback system. (For more about glucagon and the pancreas, see the chapter “How Diabetes Affects the Endocrine System.”) Glucagon can also be made synthetically and often comes in what is called a “glucagon kit,” which is often used when a person with diabetes experiences a severe hypoglycemic episode, which is when blood sugar gets too low. (For more about glucagon kits, see the chapter “Taking Charge of Diabetes.”)
What does “plasma-glucose level” mean?
Plasma-glucose level is what is referred to by most people—and throughout this book—as blood glucose level. The term plasma refers to the liquid part of the blood that remains after the blood cells have been removed. This is the part of the blood, too, that is analyzed when a person has his or her blood glucose levels checked in a laboratory or doctor’s office. All blood glucose meters are calibrated to measure the plasma-glucose level within a blood sample, although most people still say “blood glucose level.”
Is blood the only part of the body that contains glucose?
No, there are many “liquids” associated with the human body that contain glucose, not just the blood. For example, saliva, sweat, and tears contain glucose, as was known as far back as the 1930s. And of course, all the body’s cells contain glucose because they need that component for energy.
What are the most common types of diabetes?
Diabetes is commonly divided into several categories, depending on the severity, initial occurrence of the disease, and the cause of the diabetes. The most common types are prediabetes, type 1 and type 2, and gestational diabetes. (For more details about prediabetes, types 1 and 2 diabetes, gestational, and the many other forms of diabetes, see their respective chapters.) The following lists the general conditions for these forms of diabetes:
- Prediabetes (also called impaired glucose tolerance [IGT] or impaired fasting glucose [IFG], depending on the test used): When a person has blood glucose (sugar) levels above the normal range but not high enough to be diagnosable as diabetes, he or she is considered prediabetic.
- Type 1 (also seen as type I, type 1, or T1D): Also referred to as immune-mediated diabetes mellitus—formerly called insulin-dependent diabetes mellitus or juvenile diabetes. People with type 1 diabetes do not make enough insulin, the protein hormone made by the pancreas that helps the body use (and store) glucose from food.
- Type 2 (also seen as type II, type 2, or T2D): Also called insulin-resistant diabetes mellitus or adult-onset diabetes by some (although many do not use these terms anymore), type 2 diabetes usually occurs for two reasons. A person can develop type 2 diabetes when the body becomes less responsive to insulin, also known as insulin resistance. Or it can occur when the pancreas supplies too little insulin to keep up with the increased demand when a person has insulin resistance.
- Gestational diabetes: Also called gestational diabetes mellitus, it occurs during some pregnancies, but not all. It is a form of diabetes that affects between 5 and 9 percent of pregnant women (depending on the study) in the United States. There are usually no symptoms or the symptoms are mild, and it is usually found during a fasting blood glucose test.
Does eating sugar cause type 1 or type 2 diabetes?
No, eating sugar does not cause type 1 or type 2 diabetes. Neither does eating fruit or vegetables that contain various types of sugars. In fact, if a person has a healthy pancreas, eating a modest amount of sugar in its various forms can help that organ produce more insulin for the body to use.
That being said, it is thought that there are several reasons that a person develops type 2 diabetes, and many are connected to sugar. Indirectly, the disease can often be “helped along” by the ingestion of the various types of sugar. For example, if the person’s pancreas is diseased or does not function well, it can cause the body to process sugars incorrectly, which can lead to diabetes. If a person eats too many sweets, the pancreas can eventually have a difficult time handling the excess sugar, and a person can develop type 2 diabetes. If a person has a genetic predisposition to type 2 diabetes and/or overeats (often by eating too many sweets), becoming obese, this can lead to diabetes. Thus, sugar has been known to affect a person and can help lead to diabetes, but it is not the cause of the disease. (For more about sugar and diabetes, see the chapter “Diabetes and Eating.”)
Why are there so many misconceptions when it comes to understanding diabetes?
One of the main reasons for misconceptions concerning diabetes is that it comes in several different but related forms. Someone who has type 1 diabetes develops the disease differently from a person with type 2 diabetes. But because many of the symptoms of the disease are similar and often overlap, many people confuse the true causes behind the two types.
Many other misconceptions about diabetes originated from how the disease was treated over the past century. For example, even the common phrase “I have sugar”—usually meant to indicate that a person has diabetes—is why most people think eating too much sugar will cause the disease, but this is definitely a myth (see sidebar).
If a person is overweight or obese, will he or she always develop type 2 diabetes?
No, not everyone who is overweight or obese will develop type 2 diabetes. In fact, some people who are normal weight or even moderately overweight can develop the disease. But having such extra weight often means the person has a higher risk for the disease. There also are other factors, such as family history (genetics), age (older people are more at risk to develop the disease), and ethnicity, that can also mean a higher risk of developing type 2 diabetes. (For more about diabetes and obesity, see the chapter “Diabetes and Obesity.”)