• Highlights
• Introduction
• Causes
• Risk Factors
• Symptoms
• Emergency Complications
• Screening Tests
• Treatment
• Lifestyle Changes
• Medications
• Long-Term Complications
• Resources
• References

Diabetes - type 2

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of type 2 diabetes.

Alternative Names

Type 2 diabetes; Maturity onset diabetes; Noninsulin-dependent diabetes

Screening Tests

There are no clear-cut guidelines for when to screen for diabetes. Some experts recommend that everyone over age 45 be tested regularly for diabetes, although others do not feel this necessary in people without symptoms or risk factors. In fact, early screening may identify some people with impaired glucose levels that would eventually normalize. Such people might be treated unnecessarily with medications that pose a risk for high blood sugar (hypoglycemia).

Still, given the risk for serious complications with diabetes and the potential value of early treatments, most experts recommend that all adults over 45 be screened and that younger adults be screened if they have one or more of the following conditions:

• A weight that is 20% more than ideal body weight
• Risk factors for heart disease (high blood pressure, unhealthy cholesterol levels -- especially for patients with low HDL cholesterol and high triglyceride levels
• A close relative with diabetes
• A high-risk ethnic group background
• In women, having delivered a baby weighing over 9 pounds or having a history of gestational diabetes

Some experts recommend that children over age 10 should be tested for type 2 diabetes (even if they have no symptoms), if they are overweight and have at least two of the above mentioned risk factors.

Testing for Diabetes

Fasting Plasma Glucose. The fasting plasma glucose (FPG) test is the standard test for diabetes. It is a simple blood test taken after 8 hours of fasting. Results indicate:

• FPG levels are considered normal up to 100 mg/dL (or 5.5 mmol/L).
• Levels between 100 and 125 mg/dL (5.5 to 7.0 mmol/L) are referred to as impaired fasting glucose or pre-diabetes . These levels are considered to be risk factors for type 2 diabetes and its complications.
• Diabetes is diagnosed when FPG levels are 126 mg/dL (7.0 mmol/L) or higher.

The FPG test is not always reliable, so a repeat test is recommended if the initial test suggests the presence of diabetes, or if the test is normal in people who have symptoms or risk factors for diabetes. For example, people who take the test in the afternoon and show normal results may actually have abnormal levels that would be revealed if they were tested in the morning.

A 2005 study suggested that even people with FPG levels in the high end of the normal range (high 90s) may be at increased risk for developing type 2 diabetes. Obesity further increases this risk. Patients with FPG levels in the upper 90s should strive to exercise and lose weight to help lower their FPG levels.

Glucose Tolerance Test. The oral glucose tolerance test (OGTT) is more complex than the FPG and may overdiagnose diabetes in people who do not have it. Some experts recommend it as a follow-up after FPG, if the latter test results are normal but the patient has symptoms or risk factors of diabetes. The test uses the following procedures:

• It first uses an FPG test.
• A blood test is then taken 2 hours later after drinking a special glucose solution.

The following results suggest different conditions:

• OGTT levels are considered normal up to 140 mg/dL.
• Levels between 140 mg/dL and 199 mg/dL are referred to as impaired glucose tolerance or pre-diabetes.
• Diabetes is diagnosed when OGTT levels are 200 mg/dL or higher.

Both the FPG and OGTT require that the patient not eat for at least 8 hours prior to the test.

Test for Glycated Hemoglobin. Tests for blood levels of glycated hemoglobin , also known as hemoglobin A1c (HbA1c) are not currently used for an initial diagnosis, but they are useful for determining the severity of diabetes. Some experts think this test can help predict complications in people who have FPG levels between 110 and 139, which are above normal but do not indicate full-blown diabetes.

The basis for its use as a diagnostic measurement in diabetes is as follows:

• Hemoglobin is a protein molecule found in red blood cells. When glucose binds to it, the hemoglobin becomes modified, a process called glycosylation .
• Glycosylation affects a number of proteins, and elevated levels of glycolated hemoglobin are strongly associated with complications of diabetes.
• A glycated hemoglobin level of 1% above normal range identifies diabetes in 98% of patients. Normal HbA1c levels do not necessarily rule out diabetes, but if diabetes is present and levels are normal, the risk for complications is low.

The test is not affected by food intake so it can be taken at any time. A home test has been developed that might make it easier to measure HbA1c. In general, measurements suggest the following:

• Normal HbA1c levels should be below 7%.
• Levels of 11 - 12% glycolated hemoglobin indicate poor control of carbohydrates. High levels are also markers for kidney trouble.

Testing for Insulin Resistance. Investigators hope that some day a simple test for insulin resistance will be available that will be able to identify people at risk for diabetes. The presence of insulin resistance may also be a predictor of heart disease, independent of the presence of diabetes. Some research suggests that measuring insulin and triglyceride levels during a fasting period may predict a person's sensitivity to insulin.

Screening Tests for Complications

Screening for Heart Disease. All patients with diabetes should be tested for hypertension and unhealthy cholesterol and lipid levels and given an electrocardiogram. For cholesterol, people with diabetes should aim for LDL levels below 100 mg/dL, HDL levels over 50 mg/dL, and triglyceride levels below 150 mg/dL. Blood pressure goals should be 130/80 mmHg or lower. Other tests may be needed in patients with signs of heart disease.

Screening for Kidney Damage. The earliest manifestation of kidney damage is microalbuminuria, in which tiny amounts (30 to 300 mg per day) of protein called albumin are found in the urine. About 20% of type 2 patients show evidence of microalbuminuria upon diagnosis of diabetes. (However, only a small percentage of people with type 2 diabetes eventually develop kidney disease.) Microalbuminuria typically shows up in patients with type 2 diabetes who have high blood pressure.

The American Diabetes Association recommends that people with diabetes receive an annual microalbuminuria urine test. Patients should also have their blood creatinine tested at least once a year. Creatinine is a waste product that is removed from the blood by the kidneys. High levels of creatinine may indicate kidney damage. A doctor uses the results from a creatinine blood test to calculate the glomerular filtration rate (GFR). The GFR is an indicator of kidney function; it estimates how well the kidneys are cleansing the blood.

Screening for Thyroid Abnormalities. Thyroid function tests should be administered.

• Review Date: 7/15/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process . A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.