Diabetes and Insulin Resistance
Diabetes is a chronic metabolic disorder in which the body doesn't produce or properly use insulin, a hormone that is made in the pancreas and is essential for the healthy functioning of all cells in the body. After a meal, the digestive system breaks most food down into glucose, a form of sugar that travels in the bloodstream throughout the body and powers cellular activity. In the blood and in the brain, insulin helps glucose enter cells. As glucose levels rise in the blood after a meal, the pancreas releases insulin to help cells take in and use the glucose. Insulin released by the pancreas after a meal and throughout the day is transported into the brain, where it has important effects on brain function.
About 5-10 percent of people with diabetes have type 1 diabetes, an autoimmune disease that attacks the pancreas so that it can no longer make insulin. By far, the more common form of diabetes is type 2, a condition in which the pancreas makes enough insulin, but the cells do not respond properly to it—a condition called insulin resistance.
In insulin resistance, the pancreas works overtime to make more insulin to help glucose enter cells, so insulin levels rise in the blood. No matter how much insulin the pancreas produces, it can't control glucose levels, and glucose builds up in the blood, creating high blood glucose levels. Many people with insulin resistance have high levels of both glucose and insulin in their blood. When a certain threshold is crossed, a person will be diagnosed with type 2 diabetes.
Risk factors for insulin resistance and type 2 diabetes are obesity (particularly excess fat at the waist), lack of exercise, increased age, and genetic factors. Many people with type 2 diabetes have no symptoms at first. When symptoms begin to emerge, they can include infections, vision problems, nerve damage, extreme thirst, and fatigue. Over time, diabetes damages the heart, blood vessels, eyes, kidneys, and nerves. These complications can be reduced by managing blood glucose levels through weight control, diet, exercise, medications and, sometimes, the administration of insulin injections.
Type 2 diabetes affects almost one fifth of Americans over sixty. More than twenty-three million Americans have diabetes, including nearly six million who don't know they have it. Millions of others have insulin resistance. "With the increase in obesity, the lack of physical activity, and changes in our diet," Dr. Craft told us, "this is a rapidly growing condition."
Next: Insulin in the Brain
Excerpted from THE ALZHEIMER'S PROJECT: MOMENTUM IN SCIENCE, published by Public Affairs, www.publicaffairsbooks.com.
In This Section
- Vascular Disease
- Insulin Resistance and Diabetes
- Connecting Alzheimer's Disease to Vascular Disease
- Vascular Injury
- Vascular Dementia and Alzheimer's Disease
- The Problem of Cholesterol
- What's Good for the Heart is Good for the Brain
- Atherosclerosis and Alzheimer's Disease
- Associating Alzheimer's Disease with Insulin Resistance and Diabetes
- Diabetes and Insulin Resistance
- Insulin in the Brain
Momentum in Science: The Supplementary Series
- Understanding and Attacking Alzheimer's 12 min
- How Far We Have Come in Alzheimer's Research 15 min
- Identifying Mild Cognitive Impairment 20 min
- The Role of Genetics in Alzheimer's 12 min
- Advances in Brain Imaging 11 min
- Looking Into the Future of Alzheimer's 6 min
- The Connection Between Insulin and Alzheimer's 21 min
- Inflammation, the Immune System, and Alzheimer's 29 min
- The Benefit of Diet and Exercise in Alzheimer's 16 min
- Cognitive Reserve: What the Religious Orders Study is Revealing about Alzheimer's 20 min
- Searching for an Alzheimer's Cure: The Story of Flurizan 30 min
- The Pulse of Drug Development 15 min
- The DeMoe Family: Early-Onset Alzheimer's Genetics 25 min
- The Nanney/Felts Family: Late-Onset Alzheimer's Genetics 20 min
- The Quest for Biomarkers 17 min
Video: Inside the Brain: Unraveling the Mystery of Alzheimer's Disease
This 4-minute captioned video shows the progression of Alzheimer's disease in the brain.
Inside the Brain: An Interactive Tour
The Brain Tour explains how the brain works and how Alzheimer's affects it.
Alzheimer's Disease: Unraveling the Mystery
This book explains what AD is, describes the main areas in which researchers are working, and highlights new approaches for helping families and friends care for people with AD.
- About The Scientists
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- Rapid advances in our knowledge about AD have led to the development of promising new drugs and treatment strategies. However, before these new strategies can be used in clinical practice, they must be shown to work in people. Advances in prevention and treatment are only possible thanks to volunteers who participate in clinical trials.
- Among those touched by Alzheimer's (excluding self), nearly one-third provide support as a friend or relative, another 3% provide support as a healthcare professional, and the remaining two-thirds provide no support to the person suffering from Alzheimer's. When support is provided, it most often entails emotional support, followed by care-giving support. While small in comparison, more than one person in ten is providing financial support. Read more.