Many cells in the body contain special proteins called receptors that bind to insulin. They work like a lock and key. In order for glucose to enter a cell, insulin (the key) must first fit into the insulin receptor (the lock). In addition to working as a key in a lock, insulin performs other important jobs. It inhibits the release of glucose and other substances from the liver and helps make proteins in the body. So, problems with insulin production or resistance can also make the liver release too much glucose.
Diabetes is a progressive disease. Initially, the pancreas produces enough insulin to overcome these problems. But over the course of several years, the pancreas no longer makes enough insulin or releases it too slowly. Without enough insulin to meet the body’s needs, glucose levels rise and diabetes develops.
Scientists do not know why the pancreas stops working in people with type 2 diabetes. Some believe that the system that tells the pancreas to make more insulin is broken. Others think that the pancreas—after many years of working overtime to overcome insulin resistance—simply burns out.
Genes and Family History
Genes and family history appear to play a strong role in the development of type 2 diabetes—an even stronger role than in type 1 diabetes. For example, if a person with type 1 diabetes has an identical twin, there is a 25–50% chance that the twin will develop diabetes. But if a person with type 2 diabetes has an identical twin, there is a 60–75% chance that the twin will develop diabetes.
The way in which genes interact to cause diabetes is an extremely complex process that scientists are only just beginning to understand. There is no known “type 2 diabetes gene.” And it is likely that a large number of genes interact to cause type 2 diabetes. Some of the most promising studies have been done since scientists decoded the DNA of the human genome.
With the sequence of the human genome in hand, scientists have been able to link mutations in certain genes to type 2 diabetes. It appears that people pass these mutations down to family members through their DNA.
Race and Ethnicity
More evidence for the role of genes in type 2 diabetes comes from studying certain ethnic groups. African Americans, Asian Americans, Hispanics (except Cuban Americans), and Native Americans all get type 2 diabetes more than whites.
Incidence of Diabetes by Ethnicity
• 7.1% of non-Hispanic whites have diabetes
• 8.4% of Asian Americans have diabetes
• 11.8% of Hispanics have diabetes
• 12.6% of African Americans have diabetes
• 16.1% of Native Americans have diabetes
According to the “National Diabetes Fact Sheet, 2011,” from the Centers for Disease Control and Prevention.
The unusually high rate of diabetes in Native Americans also holds true for their children. Unfortunately, 4.5 out of 1,000 Native American children have diabetes, with rates as high as 50 out of every 1,000 children in the Pima Indian tribe in Arizona.
Obesity
Type 2 diabetes tends to develop in people who have extra body fat. Three-fourths of all people with type 2 diabetes are or have been obese. Body mass index measures your body’s amount of fat based on your height and weight. A body mass index of 30 or above is considered obese.
Scientists also think that some people may have genes that put them at a higher risk for obesity—and thus diabetes.
In some way, having too much body fat promotes resistance to insulin. This is why, for so many years, type 2 diabetes has been treated with changes to food and physical activity. Losing weight and increasing muscle while decreasing fat helps your body use insulin better.
Body Shape and Obesity
Your body shape may help determine your risk of developing type 2 diabetes. Extra fat above the hips (central body obesity or having a body shaped like an apple) is riskier than having extra fat in the hips and thighs (having a body shaped like a pear). Central body obesity, as well as overall obesity, is more common in African Americans than whites, which helps explain why diabetes is more common in African Americans.
Sweet Tooth
You can’t get diabetes from eating too much sugar. However, eating too much sugar isn’t good for anyone. Sweets contain lots of carbohydrates and calories, which can lead to excess pounds. Eating too much of anything (including sweets) can lead to obesity—and diabetes.
Age and Lifestyle
Age is also a risk factor for type 2 diabetes. Half of all new cases of type 2 diabetes occur in people over 55 years of age. People also tend to gain weight as they get older, so perhaps diabetes occurs more often in older people as they put on extra pounds.
Leading an inactive, sedentary lifestyle can also lead to obesity and diabetes. You’ll find out more about getting and staying in shape with your diabetes in chapter 11.
Prevention
It may sound like a no-brainer, but the best way to prevent type 2 diabetes is to be fit and to maintain a healthy weight. Okay, that’s a lot easier said than done. However, knowing it can be done is encouraging!
Studies show that people at high risk for diabetes may be able to prevent diabetes with weight loss, healthy eating, and exercise.
One of the most famous studies that looked at the prevention of type 2 diabetes is called the Diabetes Prevention Program or DPP. Scientists studied whether changing lifestyle habits, such as choosing healthier foods and physical activity, or taking diabetes medication could delay or prevent type 2 diabetes in people at high risk for the disease. The study ended a year early, when scientists discovered some amazing results!
DPP Study Results
• People who lost about 7% of their body weight through eating well and increasing their physical activity (30 minutes a day five times a week) had a 58% lower incidence of diabetes than people who took a placebo (dummy pill).
• People in the study who took the diabetes medication metformin had 31% lower incidence of diabetes than people who took a placebo.
Management and Treatment
With all the talk about the importance of eating well and exercising, you’re probably guessing that these two areas play a big role in managing your diabetes. Yes, living a healthy lifestyle is one of the most important things that you can do for yourself and your diabetes. If needed, there are additional options for managing your diabetes, including diabetes pills and insulin. Pancreas or islet transplantation is not usually an option in type 2 diabetes.
Common Goals for Living with Diabetes
• Prevent short-term problems, such as too low or too high glucose.
• Prevent or delay long-term health problems, such as heart disease and damage to nerves, kidneys, and eyes.
• Maintain a healthy lifestyle and keep doing things you enjoy, like exercising, working, and socializing.
How you manage your diabetes depends on your personal goals and needs. There are a number of different options for treating type 2 diabetes. Work with your health care providers to come up with a plan for managing your diabetes and meeting your goals (you’ll find more about this topic in chapter