Type 2 Diabetes Mellitus

Type 2 Diabetes Mellitus

What Is It?

Type 2 diabetes is a chronic disease. It is characterized by high levels of sugar in the blood. Type 2 diabetes is also called type 2 diabetes mellitus, adult-onset diabetes, non-insulin-dependent diabetes, or just diabetes.

Type 2 diabetes affects the way the body processes and uses carbohydrates, fats and proteins. During digestion, food is broken down into its basic components. The liver processes these nutrients into one type of sugar—glucose. Glucose is the most basic fuel for the body.

Glucose enters your body's cells with the help of insulin. Insulin is a hormone produced by the pancreas. Without insulin, glucose cannot pass through the cell wall.

Type 2 diabetes occurs when your body's cells do not react efficiently to insulin. This condition is called insulin resistance.

In people with insulin resistance, the pancreas first makes extra insulin to maintain a normal blood sugar. Over time, the body's insulin resistance gets worse. The pancreas cannot keep up with the demand for more and more insulin. As a result, blood glucose levels rise.

Type 2 diabetes runs in families. It most often affects people who are older than 40. But type 2 diabetes is now being seen in more and more young people. Obesity greatly increases the risk of diabetes.


The symptoms of diabetes are related to high blood glucose levels. They include:

  • Excessive urination, thirst and hunger

  • Weight loss

  • Increased susceptibility to infections, especially yeast or fungal infections

Extremely high blood sugar levels can lead to a dangerous complication called hyperosmolar syndrome. This is a life-threatening form of dehydration. In some cases, hyperosmolar syndrome is the first sign that a person has type 2 diabetes. It causes confused thinking, weakness, nausea and even seizure and coma.

People with type 2 diabetes take medications to reduce blood sugar. But these medications may cause sugar levels to drop below normal. Low blood sugar is called hypoglycemia. Symptoms of hypoglycemia include:

  • Sweating

  • Trembling

  • Dizziness

  • Hunger

  • Confusion

  • Seizures and loss of consciousness (if hypoglycemia is not recognized and corrected)

You can correct hypoglycemia by eating or drinking something with carbohydrates. This raises your blood sugar level.

Type 2 diabetes affects all parts of the body. It can cause serious, potentially life-threatening complications. These include:

  • Atherosclerosis — Atherosclerosis is fat buildup in the artery walls. This can impair blood flow to the all the organs. The heart, brain and legs are most often affected.

  • Retinopathy — Tiny blood vessels at the back of the eye become damaged by high blood sugar. Caught early, retinopathy damage can be minimized by tightly controlling blood sugar and using laser therapy. Untreated retinopathy can lead to blindness.

  • Neuropathy — This is nerve damage. The most common type is peripheral neuropathy. The nerves to the legs are damaged first, causing pain and numbness in the feet. This can advance to cause symptoms in the legs and hands. Damage to the nerves that control digestion, sexual function and urination can also occur.

  • Foot problems — Sores and blisters on the feet occur for two reasons:

    • If peripheral neuropathy causes numbness, the person will not feel irritation in the foot. The skin can break down and form an ulcer.

    • Blood circulation can be poor, leading to slow healing. Left untreated, a simple sore can become infected and very large.

  • Nephropathy — Damage to the kidneys. This is more likely if blood sugars remain elevated and high blood pressure is not treated aggressively.


Diabetes is diagnosed by testing the blood for sugar levels. Blood is tested in the morning after you have fasted overnight.

Typically, the body keeps blood sugar levels between 70 and 100 milligrams per deciliter (mg/dL), even after fasting. If a blood sugar level after fasting is greater than 125 mg/dL, diabetes is diagnosed.

Your doctor will examine you to look for signs of diabetes complications. These include:

  • Obesity, especially abdominal obesity.

  • High blood pressure

  • Deposits of blood, or puffy yellow spots in the retina of your eyes

  • Decreased sensation in the legs

  • Weak pulses in the feet

  • Abnormal pulses in the abdomen

  • Blisters, ulcers or infections of the feet

Laboratory tests are also used routinely to evaluate diabetes. These include:

  • Fasting glucose. A test of your blood sugar level after you have not eaten for several hours.

  • Hemoglobin A1C (HbA1c). Indicates how close to average your blood glucose has been during the previous two months.

  • Blood creatinine and urine microalbumin. Tests for evidence of kidney disease.

  • Lipid profile. Measures levels of triglycerides and total, HDL, and LDL cholesterol. This evaluates the risk of atherosclerosis.

Expected Duration

Diabetes is a lifelong illness.

Aging and episodic illness can cause the body's insulin resistance to increase. As a result, additional treatment typically is required over time.


You can help to prevent type 2 diabetes by:

  • Maintaining your ideal body weight. This is especially true if you have a family history of diabetes.

  • Eating a healthy diet and getting regular exercise. These delay the onset of diabetes in people who are in the early stages of insulin resistance.

  • Taking medication. The medication metformin (Glucophage) offers some additional protection for people with pre-diabetes. Pre-diabetes is defined as blood glucose levels between 100 and 125 mg/dL.

If you already have type 2 diabetes, you can still delay or prevent complications:

  • Keep tight control of your blood sugar. This reduces the risk of most complications.

  • Lower your risk of heart-related complications by:

    • Taking a daily aspirin.

    • Aggressively managing other risk factors for atherosclerosis, such as:

      • High blood pressure

      • High cholesterol and triglycerides

      • Cigarette smoking

      • Obesity

  • Visit an eye doctor and a foot specialist every year to reduce eye and foot complications.


In most cases, type 2 diabetes treatment begins with weight reduction through diet and exercise. A healthy diet for a person with diabetes is:

  • Low in cholesterol

  • Low in total calories

  • Nutritionally balanced with abundant amounts of:

    • Whole-grain foods

    • Monounsaturated oils

    • Fruits and vegetables

A daily multivitamin is recommended for most people with diabetes.

Type 2 diabetes can be controlled with medications—pills or injections.

Medicines for type 2 diabetes work in many different ways. They include medications that:

  • Improve insulin resistance in the muscles and liver.

  • Increase the amount of insulin made and released by the pancreas.

  • Cause a burst of insulin release with each meal.

  • Delay the absorption of sugars from the intestine.

  • Slow your digestion.

  • Reduce your appetite for large meals.

  • Add to your own insulin supply. This is given as an insulin injection. With enough insulin, you can adequately process glucose despite having insulin resistance.

  • Decrease the conversion of fat to glucose and improve insulin resistance. These medications are called thiazolidinediones. One medication in this group has recently been linked to heart disease. As a result, drugs from this group are not recommended as a first choice in treatment.

About one of three people with type 2 diabetes use injectable insulin regularly. Insulin often is used in small doses before bed. This helps prevent the liver from producing and releasing glucose during sleep.

In advanced type 2 diabetes, or for people who want to tightly control glucose levels, insulin may be needed more than once per day and in higher doses.

Treatment plans that include both very long-acting insulin and very short-acting insulin are frequently the most successful for controlling blood sugar. Doses of very short-acting insulin can be adjusted to accommodate inconsistent eating patterns.

Medications used to treat type 2 diabetes can have side effects. These vary by medication. Side effects may include:

  • Low blood sugar levels (hypoglycemia)

  • Weight gain

  • Nausea

  • Diarrhea

  • Life-threatening buildup of lactic acid in the blood (in people with kidney failure)

  • Leg swelling

  • Worsening of heart failure

  • Liver inflammation

  • Increased risk of heart attack (with one of the thiazolidinediones medicines)

  • Excessive gas and bloating

Although diabetes treatments, like all treatments, can cause side-effects, the benefits generally greatly outweigh the risks.

Medicines are also available to reduce the risk or to slow the onset of complications. These include medications that:

  • Slow the worsening of kidney disease.

  • Lower cholesterol. All diabetics should consider taking medication to lower their cholesterol.

  • Lower blood pressure. Diabetics should use medication to control high blood pressure if it can't be improved by lifestyle changes.

  • Protect against heart attacks. Most people with diabetes benefit from a daily aspirin.

When To Call a Professional

If you have diabetes, see your doctor regularly.

People with high blood sugar levels have a higher risk of dehydration. Contact your doctor immediately if you develop vomiting or diarrhea and are not able to drink enough fluids.

Monitor your blood sugar as advised by your health care team. Report any significant deviations in blood sugar levels.


Your treatment plan is likely to require adjustment over time. Insulin resistance increases with age. And the insulin-producing cells in the pancreas may wear out as the pancreas tries to keep up with the body's extra insulin needs.

After the first few years, the majority of people with type 2 diabetes require more than one medicine to keep their blood sugar controlled. About one out of three people with type 2 diabetes requires insulin.

The prognosis in people with type 2 diabetes varies. It depends on how well an individual modifies their risk of complications. Heart attack, stroke and kidney disease can result in premature death. Disability due to blindness, amputation, heart disease, stroke and nerve damage may occur. Some people with type 2 diabetes become dependent on dialysis treatments because of kidney failure.

There is a tremendous amount you can do to decrease your risk of complications:

  • Eat a healthy diet

  • Get regular exercise

  • Pay careful attention to your blood sugar levels

  • Reduce your other risks of heart disease

Additional Info

American Diabetes Association
ATTN: National Call Center
1701 N. Beauregard St.
Alexandria, VA 22311
Toll-Free: 1-800-342-2383

American Dietetic Association
120 South Riverside Plaza
Suite 2000
Chicago, IL 60606-6995
Toll-Free: 1-800-877-1600

National Diabetes Information Clearinghouse
1 Information Way
Bethesda, MD 20892-3560
Phone: 301-654-3327
Toll-Free: 1-800-860-8747
Fax: 301-907-8906

National Institute of Diabetes & Digestive & Kidney Disorders
Office of Communications and Public Liaison
Building 31, Room 9A04
31 Center Drive, MSC 2560
Bethesda, MD 20892-2560
Phone: 301-496-4000

Weight-Control Information Network
1 Win Way
Bethesda, MD 20892-3665
Phone: 202-828-1025
Toll-Free: 1-877-946-4627
Fax: 202-828-1028