American Diabetes Association Complete Guide to Diabetes: The Ultimate Home Reference from the Diabetes Experts


Type 2 Diabetes

• Early Symptoms and Tests

• Causes and Risk Factors

• Prevention

• Management and Treatment

Most people (about 95%) with diabetes have type 2 diabetes. Type 2 diabetes tends to develop in people over 40 and used to be called adult-onset diabetes. If you’re reading this chapter, you or someone you love has probably been diagnosed with type 2 diabetes.

However, in recent years, more children and teens are developing type 2 diabetes. Much of this has to do with kids becoming obese and inactive.

Early Symptoms and Tests

Usually, type 2 diabetes does not appear suddenly. Instead, you may have no noticeable symptoms or only mild symptoms for years before diabetes is detected, perhaps during a routine exam or blood test.

Common Symptoms of Type 2 Diabetes

• Frequent urination due to the body trying to flush out excess glucose

• Increased thirst due to dehydration

• Fatigue because the necessary glucose is not getting to your cells

• Blurred vision due to a buildup of fluid in your eyes or elevated glucose levels

• More frequent or slower-healing infections

Tests for Type 2 Diabetes

If your doctor suspects diabetes, he or she will perform a blood test, such as the A1C, fasting plasma glucose test, or the random plasma glucose test, as discussed in chapter 2. If your A1C is 6.5% or higher, your fasting plasma glucose test is 126 mg/dl or higher, or your random plasma glucose test is 200 mg/dl or higher, you will be diagnosed with diabetes. Usually, a second test will be done to confirm the diagnosis.

Causes and Risk Factors

Initially, people with type 2 diabetes will usually make insulin for some time, unlike people with type 1 diabetes, who stop making insulin once their diabetes fully develops. However, sometimes people with type 2 diabetes do not respond properly to insulin (this is called insulin resistance), or their body doesn’t produce enough insulin, or both. These problems lead to the same outcome: insulin cannot deliver glucose to the cells that need it and glucose builds up in the blood.

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.


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.


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 9).

For now, though, let’s talk about some of the basics in managing type 2 diabetes.

Tips on Managing Type 2 Diabetes

• Not everyone with type 2 diabetes needs pills or insulin when they are diagnosed.

• Some people who are newly diagnosed can begin with new meal and physical activity plans. For many, eating healthy food portions and exercising regularly keep blood glucose levels near normal.

• Your treatment plan is based on your usual blood glucose levels. Ideally, you will want to keep your blood glucose levels as close to normal as possible.

• For most people, the goal is to keep blood glucose levels between 70 and 130 mg/dl before meals and less than 180 mg/dl after meals. Your doctor may have different goals for you.

Food and Physical Activity

For many, treatment for type 2 diabetes means a balance of healthy eating and exercise. Most people with type 2 diabetes are advised to lose weight and improve their physical fitness, which can decrease weight and resistance to insulin. The severity of type 2 diabetes can be greatly reduced by maintaining a healthy body weight.

Losing a Few Pounds

Even a modest weight loss of 10–15 pounds can have benefits for your health and diabetes.

Benefits of Physical Activity and Healthy Eating

• Physical activity, such as exercise, helps by taking some glucose from the blood and using it for energy during a workout, an effect that lasts well beyond the workout.

• As your physical fitness improves with regular exercise and activity, so does your body’s sensitivity to insulin.

• Healthy eating keeps glucose levels lower.

You’ll find out more about healthy eating, physical activity, and exercise in chapters 10 and 11.

Medication for Diabetes

In addition to healthy eating and exercise, some people use pills to help manage their diabetes. These pills are called “oral diabetes medications” or “diabetes pills” because you take them by mouth instead of injecting them like insulin. In addition to pills, people with type 2 diabetes now have the option of taking injectable medications to lower their blood glucose.

If needed, you and your health care provider will work together to find the best medication for your goals and lifestyle. Only your health care provider can prescribe these medications. You’ll find out more about these medications in chapter 12.

Tips on Medication for Type 2 Diabetes

• Generally, diabetes pills are only prescribed for people with type 2 diabetes.

• At the time of diagnosis, your health care provider may prescribe a diabetes medication, as well as changes to meals and physical activity.

• Not everyone with type 2 diabetes will be helped by diabetes pills. They are more effective in people who have had high blood glucose levels for less than 10 years.

• They are more effective in people who eat healthy and who produce some insulin.


Insulin used to be considered the last resort for people with type 2 diabetes. Now, we know that starting insulin early can help keep you healthier longer.

For example, in the beginning (before you were even diagnosed) your body was becoming more and more resistant to insulin as your blood glucose levels remained high. Then, once you were diagnosed, and perhaps treated with diet and exercise or diabetes pills, your body became less resistant to insulin. Your meal plan or exercise, alone, may have been enough to keep your blood glucose levels under control.

However, for many people, the body becomes more resistant to insulin over time. In fact, you are more likely to use insulin the longer you’ve had diabetes.

It’s Not Failure

It is a big step, but taking insulin does not mean that you have failed to take care of yourself or that your diabetes is worse. It simply means that your body needs more help to keep your blood glucose levels on track.

Insulin Is Common for Type 2 Diabetes

Around 30–40% of people with type 2 diabetes use insulin. If you take insulin, it doesn’t mean your diabetes has changed from type 2 to type 1. You don’t necessarily have type 1 diabetes just because you need insulin. Instead, you are one of many people with type 2 diabetes who uses insulin because it is a helpful treatment option.

Tips for Getting Started

• Find a health care provider who can help you with insulin instructions, injection techniques, and schedules.

• Taking insulin can be intimidating. Find someone you can talk to about getting started. Often people say they wished they’d started taking insulin sooner because it gave them more energy.

You’ll find more information about insulin and insulin plans in chapter 13. There are several different ways to begin taking insulin. You’ll work with your health care provider to develop an insulin plan that is best for you.

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