Type 2 Diabetes Mellitus


What Is It?

Diabetes mellitus, commonly called just diabetes, is a common disorder that affects the way the body processes and uses carbohydrates, fats and proteins. Each of these nutrients is a source of glucose (sugar), which is the most basic fuel for the body. The most obvious sign of diabetes is a high level of sugar in the blood.

Glucose enters body cells with the help of a hormone called insulin, which acts somewhat like a gatekeeper. Without insulin, which is produced by the pancreas, glucose cannot pass through the cell wall, and the cell “starves.” Type 2 diabetes occurs when your body’s cells do not react efficiently to insulin produced by the pancreas, a condition called insulin resistance. In people with insulin resistance, the pancreas at first manufactures extra insulin to maintain a normal blood sugar. Eventually, as the body’s insulin resistance progresses, the pancreas is unable to keep up with the demand for more and more insulin, and blood-glucose levels rise.

About 95 percent of people with diabetes have type 2 diabetes, also called adult-onset diabetes or non-insulin-dependent diabetes. Type 2 diabetes runs in families, and it commonly affects people who are older than 40. With the rise in obesity that has been seen in the United States in the last decade, type 2 diabetes increasingly is being seen in younger people, particularly African-Americans, Hispanics, and American Indians. Obesity, especially central obesity, greatly increases the risk of diabetes. Central obesity occurs when more fat accumulates around the waist than in the hip area. This is the fat pattern that often is associated with insulin resistance and a condition known as metabolic syndrome.

Metabolic syndrome, originally called syndrome X, is a set of abnormalities that increase the risk of heart disease and stroke. The hallmarks of the metabolic syndrome include obesity, insulin resistance with high-normal or slightly elevated blood sugar, increased blood levels of insulin (hyperinsulinemia), high blood pressure, elevated levels of triglycerides, and low levels of high-density lipoprotein (HDL) cholesterol (the “good” cholesterol). These abnormalities commonly occur together and are related to each other by a genetic or metabolic link. Both the metabolic syndrome and type 2 diabetes increase the risk of heart disease, stroke and peripheral artery disease.


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 of the skin and vagina

Extremely high blood-sugar levels can lead to a dangerous complication called hyperosmolar syndrome, also known as hyperosmolar hyperglycemic nonketotic syndrome (HHNS), hyperosmolar hyperglycemic state (HHS), or hyperosmolar coma. Hyperosmolar syndrome is a life-threatening form of dehydration that can result from untreated high blood-sugar levels. Hyperosmolar syndrome can complicate a severe acute illness, such as a Stroke; it can also happen when poor fluid intake triggers dehydration. In some cases, hyperosmolar coma is the first sign that a person has type 2 diabetes.

When people with type 2 diabetes take medications to reduce blood sugar, sugar levels may drop below the normal range and cause hypoglycemia (low blood sugar). Symptoms of hypoglycemia include sweating, trembling, dizziness, hunger and confusion. Hypoglycemia that you do not recognize and correct can lead to seizures and loss of consciousness. You can correct hypoglycemia (raise blood-sugar levels) by eating or drinking something with carbohydrates.

Type 2 diabetes affects all body systems and can cause serious, potentially life-threatening complications, including:

  • Atherosclerosis — Metabolic syndrome and type 2 diabetes are associated with 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 — In this disorder, tiny blood vessels at the back of the eye are damaged by high blood sugar. Caught early, retinopathy damage can be minimized by regaining tight control of blood sugar and by using laser therapy. Untreated retinopathy can lead to blindness.

  • Neuropathy — This is nerve damage. The most common type is peripheral neuropathy. The longest nerves in the body, the ones to the legs, are damaged first causing pain and numbness in the feet. This can advance to cause symptoms in the legs and hands. Autonomic neuropathy is damage to the nerves that control vital autonomic functions, such as digestion, sexual function and urination.

  • Foot problems — Sores and blisters occur for two reasons. If peripheral neuropathy causes numbness, the person will not feel an irritation or pressure point in the foot. The skin can break down and form an ulcer. Also, 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 is more likely if blood sugars remain persistently elevated and high blood pressure in not treated aggressively.


Diabetes is diagnosed by testing the blood for sugar levels. Blood is taken in the morning after you have fasted overnight. Typically, the body keeps blood-sugar levels between 65 and 110 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 that you have complications or risk factors that increase the risk of complications. These include:

  • Obesity, especially abdominal obesity (waist circumferences greater than 40 inches in men or 35 inches in women)
  • High Blood Pressure
  • Deposits or areas that have leaked blood on your retina, seen through an instrument called an ophthalmoscope during an eye examination
  • Decreased sensation in the legs
  • Weak pulses in the feet or an abnormal pulses in the abdomen
  • Blisters, ulcers or infections of the feet

Laboratory tests that are used routinely to evaluate diabetes include:

  • Fasting glucose, a test of your blood-sugar level after you have not eaten for several hours
  • Hemoglobin A1C, which indicates how close to average your blood glucose has been during the previous two months
  • Blood creatinine and urine microalbumin for evidence of kidney disease
  • Lipid profile (cholesterol, triglycerides, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol) to evaluate the risk of atherosclerosis

Expected Duration

Diabetes is a lifelong illness. Aging and episodic illness can cause the body’s insulin resistance to increase, so additional treatment typically is required over time.


You can help to prevent type 2 diabetes by maintaining your ideal body weight, especially if you have a strong family history of diabetes. Diet and exercise have been shown to delay the onset of diabetes in people who are in the early stages of insulin resistance, identified by borderline blood-sugar levels. The medication metformin (Glucophage) offers some additional protection for people with blood-glucose levels that are between 110 and 125 mg/dL, near the diabetes range. People with blood-sugar levels in this range sometimes are said to have pre-diabetes.

If you already have type 2 diabetes, you can delay or prevent complications by keeping tight control of your blood sugar. In addition, you can lower your risk of heart-related complications by taking a daily aspirin, and by aggressively managing other risk factors for atherosclerosis, such as high blood pressure, high blood levels of cholesterol and triglycerides, cigarette smoking and Obesity. Yearly visits with an eye doctor and a foot specialist (podiatrist) are recommended to reduce eye and foot complications.


In most people with 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, and 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 in most people can be controlled with medications taken by mouth (oral medications). Oral medicines for type 2 diabetes include:

  • Metformin (Glucophage), which improves insulin resistance in the muscle tissues and liver
  • Sulfonylureas, including glyburide (DiaBeta, Glynase, Micronase), glipizide (Glucotrol), and others, which increase the amount of insulin made and released by the pancreas
  • Repaglinide (Prandin) and nateglinide (Starlix), which cause a burst of insulin release with each meal,
  • Thiazolidinediones, including rosiglitazone (Avandia) and pioglitazone (Actos), which decrease the conversion of fat to glucose, and which improve insulin resistance
  • Acarbose (Precose) and miglitol (Glyset), which delay the absorption of sugars from the intestine.

Injectable insulin is used regularly by about one out of three people with type 2 diabetes. Insulin often is used in small doses before bed to help to prevent the production and release of glucose from the liver during sleep. In advanced type 2 diabetes, insulin may be needed more than once per day and in higher doses. Treatment plans that include newer forms of insulin, including very long-acting glargine insulin (Lantus) and very short-acting lispro insulin (Humalog) or aspart insulin (Novolog), are frequently the most successful ways for people with type 2 diabetes to control blood sugar. To accommodate eating patterns that vary, doses of very short-acting insulin can be adjusted depending on the amount of carbohydrates taken in with each meal.

The medications used to treat type 2 diabetes can have side effects. The major side effects of sulfonylureas, repaglinide, nateglinide and insulin are hypoglycemia (low blood-sugar levels) and weight gain. The most common side effects of metformin are nausea and diarrhea, but these are less likely to happen if the drug is taken with meals. Metformin should not be used in people with kidney failure because of the risk of a life-threatening buildup of lactic acid in the blood. Rosiglitazone and pioglitazone frequently cause weight gain and can cause leg swelling or worsen heart failure. They also may cause inflammation of the liver, so liver tests should be done every two months for a year. Acarbose, which is taken before each meal, can cause excessive gas and bloating.

Medicines are also available to reduce the risk of complications, or the rate at which complications develop. People with diabetes who have early signs of kidney damage benefit from medicines called ACE inhibitors, including lisinopril (Prinivil, Zestril), enalapril (Vasotec), benazepril (Lotensin) and others or medicines called angiotensin receptor blockers, including losartan (Cozaar), valsartan (Diovan) and others). These medicines slow the advancement of kidney disease. Diabetics who have elevated low-density lipoprotein (LDL) cholesterol levels above 100 mg/dL should take medication to lower their cholesterol, usually a “statin.” Diabetics with blood pressure greater than 135/85 mmHg need to reduce the reading and often require medication. Most people with diabetes benefit from a daily aspirin which helps to protect against heart attacks.

When To Call A Professional

If you have diabetes, you should see your doctor regularly.

Because people with high blood-sugar levels have a higher risk of dehydration, you should contact your doctor immediately if you develop vomiting or diarrhea and are not able to drink enough fluids.

Monitor your blood sugars 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 cells in the pancreas that make insulin are likely to wear out as the pancreas tries to keep up with the body’s extra insulin needs. After the first few years of treatment, the majority of type 2 diabetics 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 depending on how well an individual modifies the 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. Four to six out of every 100 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. A healthy diet, regular exercise, careful attention to your blood-sugar levels, and reducing your other risks of heart disease all can help you to maintain your health and prevent complications.

Also see:
Diabetes Health Center
Diabetes - Type 1
Type-2 diabetes
Diabetes and Infections

Last Edited: Aug.18, 2015

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.