Glucose metabolism generates the energy needed to fuel the body's activities. Hormones control the level of glucose in the blood. The pancreas produces the hormone insulin in response to increased blood sugar levels. Insulin triggers the entry mechanism that allows blood sugar into the body cells, thereby lowering the glucose level. Disruptions in the production or action of insulin can lead to elevated blood sugar levels, or glucose intolerance.
Type 1 Diabetes
Destruction of the insulin-producing beta cells of the pancreas causes type 1 diabetes mellitus, explains the Juvenile Diabetes Research Foundation. Because the beta cells are the only source of insulin in the body, their destruction leads to a chronic deficiency or absence of insulin. Without insulin, the body becomes intolerant to glucose, which manifests as persistently elevated blood sugar levels.
Type 1 diabetes mellitus, formerly known as juvenile diabetes and insulin-dependent diabetes, usually presents in children and young adults with approximately 30,000 new cases diagnosed annually in the United States, according to the Juvenile Diabetes Research Foundation. Classic symptoms of undiagnosed type 1 diabetes include extreme hunger and thirst, increased urination, unintentional weight loss, weakness, lack of energy, irritability and confusion. Replacement insulin remains the primary form of treatment for the condition.
Type 2 Diabetes
Approximately 90 to 95 percent of people with diabetes mellitus in the United States have the type 2 form of the disease, according to the National Institute of Diabetes and Digestive and Kidney Diseases. With this form of diabetes, the body cells fail to respond normally to the hormone insulin, a problem known as insulin resistance. In most people with type 2 diabetes, circulating levels of insulin are normal or increased. Lack of tissue response to the hormone, however, leaves glucose circulating in the blood rather than entering the body tissues.
Obesity is strongly associated with insulin resistance and the resulting glucose intolerance of type 2 diabetes. In a 2009 study published in the "Journal of Diabetes and Its Complications," Dr. Holly Kramer and colleagues report that more than 62 percent of Americans with type 2 diabetes are obese. The "diabesity" epidemic refers to the closely linked increases in the rates of obesity and type 2 diabetes in the United States. The exact mechanisms that link obesity, insulin resistance and type 2 diabetes remain an active area of biomedical research.
Gestational Diabetes
Gestational diabetes refers to the development of glucose intolerance during pregnancy. The National Institute of Diabetes and Digestive and Kidney Diseases estimates that gestational diabetes occurs in approximately 3 percent to 8 percent of pregnancies in the United States. Pre-existing obesity and a family history of diabetes increase the risk for gestational diabetes, which represents a form of insulin resistance. Pregnancy-induced glucose intolerance typically resolves after delivery. Women who have had gestational diabetes, however, are at an increased risk for the development of type 2 diabetes mellitus.
References
- Juvenile Diabetes Research Foundation: What is Type 1 Diabetes?
- Juvenile Diabetes Research Foundation: Type 1 Diabetes Symptoms
- National Institute of Diabetes and Digestive and Kidney Diseases: Diabetes Overview
- "Journal of Diabetes and Its Complications"; Increasing BMI and Waist Circumference and Prevalence of Obesity Among Adults with Type 2 Diabetes: the National Health and Nutrition Examination Surveys; Holly Kramer, M.D., et al.; November 2009
- "Diabetes Spectrum"; Obesity and Type 2 Diabetes: The Twin Epidemic; Sonia Caprio, M.D.; October 2003
