Type 2 Diabetes

Type 2 diabetes: an introduction

Type 2 diabetes (the full name is type 2 diabetes mellitus) is a disorder of metabolism, characterized by high blood glucose. It is the most common form of diabetes, accounting for over 90% of cases and is associated with older age, a family history of the disease, obesity, a prior history of gestational diabetes (a form of the disease that can occur in pregnant women), and certain ethnic backgrounds. The role of obesity in increasing risk for type 2 diabetes is particularly prominent. An estimated 80% of people with type 2 diabetes are obese or overweight.1

What goes wrong to cause type 2 diabetes?

In type 2 diabetes, the main cause of elevated blood glucose is that the body loses the ability to use the hormone insulin effectively (this is sometimes called “insulin resistance”). Normally, insulin produced by the pancreas allows us to use the glucose we take in to satisfy our energy needs or store it away for later use.

The root cause of insulin resistance in type 2 diabetes is not known, but something goes wrong with the ability of insulin to deliver glucose into cells. In most cases of type 2 diabetes, early in the disease, the pancreas produces a sufficient amount of insulin. However, over time, with type 2 diabetes, insulin production in the pancreas can also decrease. So, type 2 diabetes can involve two different mechanisms that interfere with how insulin normally functions, insulin resistance and decreased production of insulin by the pancreas.1,2

How is type 2 diabetes different from type 1 diabetes?

Although both type 1 and type 2 diabetes are both characterized by elevated blood glucose, the cause behind this elevation is what distinguishes the two forms of diabetes. In type 1 diabetes an autoimmune process compromises the ability of the pancreas to produce insulin. By contrast, in type 2 diabetes, the main cause of elevated blood glucose is that the body loses the ability to use insulin effectively (this is sometimes called “insulin resistance”). In most cases of type 2 diabetes, early in the disease, the pancreas produces a sufficient amount of insulin. However, over time, with type 2 diabetes, insulin production in the pancreas can also decrease.1,2

In addition to the mechanisms that cause the two most common forms of diabetes, type 2 and 1 diabetes are also distinguished from one another in several important ways. Type 1 diabetes tends to first appear during the early years (before the age of 25 years), while type 2 diabetes is a disease often associated with adults over the age of 25 years. (With the current epidemic of obesity among children and adolescents in the US, type 2 diabetes is becoming more and more common in younger patients.)3

Type 2 diabetes is closely linked with obesity, while people with type 1 diabetes are typically thin. Because type 1 diabetes is an autoimmune disease in which the body’s immune system turns against the healthy beta cells in the pancreas, in people with this form of the disease a type of specialized protein called an autoantibody that has been created to attack and destroy beta cells is present in the blood. This autoantibody is not found in people with type 2 diabetes. Other features that distinguish the two forms of diabetes include insulin dependence (type 1 diabetes requires treatment with insulin, while type 2 diabetes does not), family history (there is strong genetic component to risk for type 2 diabetes, while this is not the case with type 1 diabetes), and the risk for a complication called ketoacidosis (diabetic coma), which is high in people with type 1 diabetes and low in those with type 2 disease.3

Comparing features of                           Type 1 and 2 diabetes

Features

Type 1 diabetes

Type 2 diabetes

Age at diagnosis Typically younger than 25 years (may occur at any age) Typically older than 25 years*
Weight Typically thin Most (more than 90%) overweight or obese
Autoantibodies Present Absent
Insulin dependent Yes Yes
Insulin sensitivity Normal when controlled Decreased
Family history Infrequent (5% to 10%) Frequent (75% to 90%)
Risk of diabetic coma (ketoacidosis) high low

*Frequency of type 2 diabetes is increasing in adolescents with increasing rates of obesity.

Adapted from McCulloch DK. Classification of diabetes mellitus and genetic diabetic syndromes. Nathan DM, Wolfsdorf JI, Mulder JE, eds. UptoDate. Wolters Kluwer Health. Accessed at: www.uptodate.com. 2013.

Symptoms and signs of type 2 diabetes

Typical symptoms of type 2 diabetes include fatigue, frequent urination, increased thirst and hunger, weight loss, blurred vision, and slow healing of wounds. In some people with type 2 diabetes, symptoms may not occur.1

What causes type 2 diabetes and can I do anything to reduce my risk?

As in type 2 diabetes, the main cause of elevated blood glucose in prediabetes is that the body loses the ability to use insulin effectively (this is sometimes called “insulin resistance”), with the result that glucose can not enter the cells.2

We do not understand exactly why some people are affected by type 2 diabetes and others are not. However, scientists have identified some factors that increase a person’s risk for type 2 diabetes.

Genetics. There is a strong genetic component to type 2 diabetes. In other words, if type 2 diabetes runs in your family, your chances of developing the disease are increased.4

Lifestyle factors. Research has shown that several lifestyle factors, including lack of physical activity, obesity, a certain kind of diet (high in sweets and meats), and smoking, may contribute to increaseed risk of developing type 2 diabetes.

This is good news if you have type 2 diabetes, because, unlike with genes (your stuck with them!), it’s possible to make changes to your lifestyle and reap the health benefits.

Studies have shown that obesity increases your risk for type 2 diabetes and losing weight decreases your risk, as well as improves your ability to control your blood sugar if you’ve been diagnosed with type 2 diabetes. Additionally, regular moderate physical activity—a good way to lose extra weight and improve cardiovascular fitness—has been shown to decrease risk for and improve control of type 2 diabetes.4

Eating red meat, processed meats, and beverages sweetened with sugar is associated with increased risk of developing type 2 diabetes. On the other hand, a diet rich in fruits, vegetables, nuts, whole grains, and olive oil may decrease your risk of developing type 2 diabetes and improve your ability to control your blood sugar if you have the disease. Therefore, the wisdom is to limit consumption of foods in the first group and increase consumption of foods in the second group.4

Studies have established a link between smoking and risk of developing diabetes (one study even showed that second-hand smoke increased risk). However, the link is not as clear as with obesity and lack of exercise. Additionally, quitting smoking is sometimes accompanied by weight gain. You should definitely consider kicking the habit, if you smoke, but conventional wisdom says that you should also accompany smoking cessation with a plan for losing weight and getting regular exercise.4

Learn more about healthy lifestyle change, including weight loss, diet, and exercise, to lowering blood sugar.

Lifestyle changes can make a big difference!

In fact, in a large study conducted in 3,000 individuals with impaired glucose tolerance, a healthy diet and regular exercise resulting in weight reduction of 5% to 7% (this would be about 10-14 lbs in a person weighing 200 lbs) reduced the risk of being diagnosed with type 2 diabetes by almost 60%. This demonstrates the huge potential for lifestyle changes in reducing diabetes risk. And those lifestyle changes don’t necessarily have to be extreme. To get their exercise, most participants in the study were not running marathons, but walking regularly (at least 30 minutes a day for 5 days a week).1

How is type 2 diabetes treated?

Type 2 diabetes is treated with a combination of diet, lifestyle changes, and medicine. If you have type 2 diabetes, your doctor and care team will work with to help you5:

  • Lose weight
  • Eat a healthy diet
  • Exercise regularly
  • Quit smoking

In addition to making these lifestyle changes, you may take any one of several medications used to treat type 2 diabetes. Typically, the first medication that a person with type 2 diabetes will take is called metformin (Glucophage).5
Learn more about medications for treating type 2 diabetes

Important things keep in mind…

If you have been diagnosed with type 2 diabetes or if you have been told that you are at risk for the disease, you may be feeling overwhelmed. You probably have many questions about why the disease has affected you and what it will mean for your life (both your long-term health and daily living). You may have many practical questions, concerning blood sugar testing, treatment options, and diet and nutrition.

Although getting a diagnosis of type 2 diabetes can be emotionally challenging, keep in mind some important facts. Most people with type 2 diabetes can:

  • Continue to lead full and active lives
  • Enjoy the foods and activities they have always enjoyed
  • Take part in almost any form of exercise
Written by: Jonathan Simmons | Last reviewed: May 2014.
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