Your health care professional can diagnose diabetes, prediabetes, and gestational diabetes through blood tests. The blood tests show if your blood glucose, also called blood sugar, is too high.
Do not try to diagnose yourself if you think you might have diabetes. Testing equipment that you can buy over the counter, such as a blood glucose meter, cannot diagnose diabetes.
Who should be tested for diabetes?
Anyone who has symptoms of diabetes should be tested for the disease. Some people will not have any symptoms but may have risk factors for diabetes and need to be tested. Testing allows health care professionals to find diabetes sooner and work with their patients to manage diabetes and prevent complications.
Testing also allows health care professionals to find prediabetes. Making lifestyle changes to lose a modest amount of weight if you are overweight may help you delay or prevent type 2 diabetes.
Type 1 diabetes
Most often, testing for type 1 diabetes occurs in people with diabetes symptoms. Doctors usually diagnose type 1 diabetes in children and young adults. Because type 1 diabetes can run in families, a study called TrialNet offers free testing to family members of people with the disease, even if they don’t have symptoms.
Type 2 diabetes
Experts recommend routine testing for type 2 diabetes if you
•are age 45 or older
•are between the ages of 19 and 44, are overweight or obese, and have one or more other diabetes risk factors
•are a woman who had gestational diabetes1
Medicare covers the cost of diabetes tests for people with certain risk factors for diabetes. If you have Medicare, find out if you qualify for coverage. If you have different insurance, ask your insurance company if it covers diabetes tests.
Though type 2 diabetes most often develops in adults, children also can develop type 2 diabetes. Experts recommend testing children between the ages of 10 and 18 who are overweight or obese and have at least two other risk factors for developing diabetes.1
•a mother who had diabetes while pregnant with them
•any risk factor mentioned in Risk Factors for Type 2 Diabetes
What tests are used to diagnose diabetes and prediabetes?
Health care professionals most often use the fasting plasma glucose (FPG) test or the A1C test to diagnose diabetes. In some cases, they may use a random plasma glucose (RPG) test.
Fasting plasma glucose (FPG) test
The FPG blood test measures your blood glucose level at a single point in time. For the most reliable results, it is best to have this test in the morning, after you fast for at least 8 hours. Fasting means having nothing to eat or drink except sips of water.
The A1C test is a blood test that provides your average levels of blood glucose over the past 3 months. Other names for the A1C test are hemoglobin A1C, HbA1C, glycated hemoglobin, and glycosylated hemoglobin test. You can eat and drink before this test. When it comes to using the A1C to diagnose diabetes, your doctor will consider factors such as your age and whether you have anemia or another problem with your blood.1 The A1C test is not accurate in people with anemia.
Your health care professional will report your A1C test result as a percentage, such as an A1C of 7 percent. The higher the percentage, the higher your average blood glucose levels.
People with diabetes also use information from the A1C test to help manage their diabetes.
Random plasma glucose (RPG) test
Sometimes health care professionals use the RPG test to diagnose diabetes when diabetes symptoms are present and they do not want to wait until you have fasted. You do not need to fast overnight for the RPG test. You may have this blood test at any time.
What test numbers tell me if I have diabetes or prediabetes?
Each test to detect diabetes and prediabetes uses a different measurement. Usually, the same test method needs to be repeated on a second day to diagnose diabetes. Your doctor may also use a second test method to confirm that you have diabetes.
The following table helps you understand what your test numbers mean.
Which tests help my health care professional know what kind of diabetes I have?
Even though the tests described here can confirm that you have diabetes, they can’t identify what type you have. Sometimes health care professionals are unsure if diabetes is type 1 or type 2. A rare type of diabetes that can occur in babies, called monogenic diabetes, can also be mistaken for type 1 diabetes. Treatment depends on the type of diabetes, so knowing which type you have is important.
To find out if your diabetes is type 1, your health care professional may look for certain autoantibodies. Autoantibodies are antibodies that mistakenly attack your healthy tissues and cells. The presence of one or more of several types of autoantibodies specific to diabetes is common in type 1 diabetes, but not in type 2 or monogenic diabetes. A health care professional will have to draw your blood for this test.
If you had diabetes while you were pregnant, you should get tested 6 to 12 weeks after your baby is born to see if you have type 2 diabetes.
One of the best ways to predict how well someone will manage diabetes: how much support they get from family and friends.
Daily diabetes care is a lot to handle, from taking meds, injecting insulin, and checking blood sugar to eating healthy food, being physically active, and keeping health care appointments. Your support can help make the difference between your friend or family member feeling overwhelmed or empowered.
What You Can Do
Learn about diabetes. Find out why and when blood sugar should be checked, how to recognize and handle highs and lows (more below), what lifestyle changes are needed, and where to go for information and help.
Know diabetes is individual. Each person who has diabetes is different, and their treatment plan needs to be customized to their specific needs. It may be very different from that of other people you know with diabetes.
Ask your friend or relative how you can help, and then listen to what they say. They may want reminders and assistance (or may not), and that can change over time.
Go to appointments if it’s OK with your relative or friend. You could learn more about how diabetes affects them and how you can be the most helpful.
Give them time in the daily schedule so they can manage their diabetes—check blood sugar, make healthy food, take a walk.
Avoid blame. People with diabetes are often overweight, but being overweight is just one of several factors that can lead to diabetes. And blood sugar levels can be hard to control even with a healthy diet and regular physical activity. Diabetes is complicated!
Step back. You may share the same toothpaste, but your family member may not want to share everything about managing diabetes with you. The same goes for a friend with diabetes.
Accept the ups and downs. Moods can change with blood sugar levels, from happy to sad to irritable. It might just be the diabetes talking, but ask your friend or relative tell their health care team if they feel sad on most days—it could be depression.
Be encouraging. Tell them you know how hard they’re trying. Remind them of their successes. Point out how proud you are of their progress.
Walk the talk. Follow the same healthy food and fitness plan as your loved one; it’s good for your health, too. Lifestyle changes become habits more easily when you do them together.
Help them feel the power to manage their diabetes.
Nervousness or anxiety.
Sweating, chills, or clamminess.
Irritability or impatience.
Dizziness and difficulty concentrating.
Hunger or nausea.
Weakness or fatigue.
Anger, stubbornness, or sadness.Know the lows. Hypoglycemia (low blood sugar) can be dangerous and needs to be treated immediately. Symptoms vary, so be sure to know your friend’s or relative’s particular signs, which could include
If your family member or friend has hypoglycemia several times a week, suggest that he or she talk with his or her health care team to see if the treatment plan needs to be adjusted.
Offer to help them connect with other people who share their experience. Online resources such as the American Association of Diabetes Educators’ Diabetes Online Community[1.27 MB] or in-person diabetes support groups are good ways to get started.
The most important thing is quality of life, yours and theirs. Sure, there will be highs and lows—blood sugar and otherwise—but together you can help make diabetes a part of life, instead of life feeling like it’s all about diabetes.
The 2014 Surgeon General’s Report has found that smoking is a cause of type 2 diabetes, which is also known as adult-onset diabetes. Smokers have a greater risk of developing type 2 diabetes than do nonsmokers. The risk of developing diabetes increases with the number of cigarettes smoked per day.
How smoking causes type 2 diabetes
Smoking increases in inflammation in the body. Inflammation occurs when chemicals in cigarette smoke injure cells, causing swelling and interfering with proper cell function. Smoking also causes oxidative stress, a condition that occurs as chemicals from cigarette smoke combine with oxygen in the body. This causes damage to cells. Evidence strongly suggests that both in inflammation and oxidative stress may be related to an increased risk of diabetes.
The evidence also shows that smoking is associated with a higher risk of abdominal obesity, or belly fat. Abdominal obesity is a known risk factor for diabetes because it encourages the production of cortisol, a hormone that increases blood sugar. Smokers tend to have higher concentrations of cortisol than nonsmokers.
What smoking means to people with diabetes
Studies have confirmed that when people with type 2 diabetes are exposed to high levels of nicotine, insulin (the hormone that lowers blood sugar levels) is less effective. People with diabetes who smoke need larger doses of insulin to control their blood sugar.
Smokers who have diabetes are more likely to have serious health problems, including:
heart and kidney disease;
poor blood flow in the legs and feet that can lead to foot infections, ulcers, possible amputation of toes or feet;
possible amputation of toes or feet;
retinopathy (an eye disease that can cause blindness);
peripheral neuropathy (damaged nerves to the arms and legs that cause numbness, pain, weakness, and poor coordination).
Even though we don’t know exactly which smokers will develop type 2 diabetes, we do know that all diabetic smokers should quit smoking or use any type of tobacco product immediately. The health bene ts of quitting begin right away. People with diabetes who quit have better control of their blood sugar. Studies have shown that insulin can start to become more effective at lowering blood sugar levels eight weeks after a smoker quits.
When you first found out you had diabetes, you tested your blood sugar often to understand how food, activity, stress, and illness could affect your blood sugar levels. By now, you’ve got it figured out for the most part. But then—bam! Something makes your blood sugar zoom up. You try to adjust it with food or activity or insulin, and it dips low. You’re on a rollercoaster no one with diabetes wants to ride.
Knowledge is power! Look out for these surprising triggers that can send your blood sugar soaring:
Sunburn—the pain causes stress, and stress increases blood sugar levels.
Artificial sweeteners—more research needs to be done, but some studies show they can raise blood sugar.
Coffee—even without sweetener. Some people’s blood sugar is extra-sensitive to caffeine.
Losing sleep—even just one night of too little sleep can make your body use insulin less efficiently.
Skipping breakfast—going without that morning meal can increase blood sugar after both lunch and dinner.
Time of day—blood sugar can be harder to control the later it gets.
Dawn phenomenon—people have a surge in hormones early in the morning whether they have diabetes or not. For people with diabetes, blood sugar can spike.
Dehydration—less water in your body means a higher blood sugar concentration.
Nose spray—some have chemicals that trigger your liver to make more blood sugar.
Gum disease—it’s both a complication of diabetes and a blood sugar spike.
Watch out for other triggers that can make your blood sugar fall. For example, extreme heat can cause blood vessels to dilate, which causes insulin absorb more quickly and could lead to low blood sugar. If an activity or food or situation is new, be sure to check your blood sugar levels before and after to see how you respond.
On this episode of TuDiabetes Talks, Mila interviews Dr. Karol E. Watson, to talk about the ForYourSweetheart initiative, the campaign aims to raise awareness about the risk of developing heart disease if you live with diabetes.
On this episode of TuDiabetes Talks, Mila interviews Dr. Karol E. Watson, to talk about the ForYourSweetheart initiative, the campaign aims to raise awareness about the risk of developing heart disease if you live with diabetes.
Be sure to drink water before, during, and after exercise to stay well hydrated. The following are some other tips for safe physical activity when you have diabetes.
Talk with your health care team before you start a new physical activity routine, especially if you have other health problems. Your health care team will tell you a target range for your blood glucose level and suggest how you can be active safely.
Your health care team also can help you decide the best time of day for you to do physical activity based on your daily schedule, meal plan, and diabetes medicines. If you take insulin, you need to balance the activity that you do with your insulin doses and meals so you don’t get low blood glucose.
Prevent low blood glucose
Because physical activity lowers your blood glucose, you should protect yourself against low blood glucose levels, also called hypoglycemia. You are most likely to have hypoglycemia if you take insulin or certain other diabetes medicines, such as a sulfonylurea. Hypoglycemia also can occur after a long intense workout or if you have skipped a meal before being active. Hypoglycemia can happen during or up to 24 hours after physical activity.
Planning is key to preventing hypoglycemia. For instance, if you take insulin, your health care provider might suggest you take less insulin or eat a small snack with carbohydrates before, during, or after physical activity, especially intense activity.5
You may need to check your blood glucose level before, during, and right after you are physically active.
Take care of your feet
People with diabetes may have problems with their feet because of poor blood flow and nerve damage that can result from high blood glucose levels. To help prevent foot problems, you should wear comfortable, supportive shoes and take care of your feet before, during, and after physical activity.
What physical activities should I do if I have diabetes?
Most kinds of physical activity can help you take care of your diabetes. Certain activities may be unsafe for some people, such as those with low vision or nerve damage to their feet. Ask your health care team what physical activities are safe for you. Many people choose walking with friends or family members for their activity.
Doing different types of physical activity each week will give you the most health benefits. Mixing it up also helps reduce boredom and lower your chance of getting hurt. Try these options for physical activity.
Add extra activity to your daily routine
If you have been inactive or you are trying a new activity, start slowly, with 5 to 10 minutes a day. Then add a little more time each week. Increase daily activity by spending less time in front of a TV or other screen. Try these simple ways to add physical activities in your life each day:
Walk around while you talk on the phone or during TV commercials.
Do chores, such as work in the garden, rake leaves, clean the house, or wash the car.
Park at the far end of the shopping center parking lot and walk to the store.
Take the stairs instead of the elevator.
Make your family outings active, such as a family bike ride or a walk in a park.
If you are sitting for a long time, such as working at a desk or watching TV, do some light activity for 3 minutes or more every half hour. Light activities include
leg lifts or extensions
overhead arm stretches
desk chair swivels
walking in place
Do aerobic exercise
Aerobic exercise is activity that makes your heart beat faster and makes you breathe harder. You should aim for doing aerobic exercise for 30 minutes a day most days of the week. You do not have to do all the activity at one time. You can split up these minutes into a few times throughout the day.
To get the most out of your activity, exercise at a moderate to vigorous level. Try
walking briskly or hiking
swimming or a water-aerobics class
riding a bicycle or a stationary bicycle
taking an exercise class
playing basketball, tennis, or other sports
Talk with your health care team about how to warm up and cool down before and after you exercise.
Do strength training to build muscle
Strength training is a light or moderate physical activity that builds muscle and helps keep your bones healthy. Strength training is important for both men and women. When you have more muscle and less body fat, you’ll burn more calories. Burning more calories can help you lose and keep off extra weight.
You can do strength training with hand weights, elastic bands, or weight machines. Try to do strength training two to three times a week. Start with a light weight. Slowly increase the size of your weights as your muscles become stronger.
Do stretching exercises
Stretching exercises are light or moderate physical activity. When you stretch, you increase your flexibility, lower your stress, and help prevent sore muscles.
You can choose from many types of stretching exercises. Yoga is a type of stretching that focuses on your breathing and helps you relax. Even if you have problems moving or balancing, certain types of yoga can help. For instance, chair yoga has stretches you can do when sitting in a chair or holding onto a chair while standing. Your health care team can suggest whether yoga is right for you.
The A1C test is a blood test that provides information about a person’s average levels of blood glucose, also called blood sugar, over the past 3 months. The A1C test is sometimes called the hemoglobin A1c, HbA1c, or glycohemoglobin test. The A1C test is the primary test used for diabetes management and diabetes research.
How does the A1C test work?
The A1C test is based on the attachment of glucose to hemoglobin, the protein in red blood cells that carries oxygen. In the body, red blood cells are constantly forming and dying, but typically they live for about 3 months. Thus, the A1C test reflects the average of a person’s blood glucose levels over the past 3 months. The A1C test result is reported as a percentage. The higher the percentage, the higher a person’s blood glucose levels have been. A normal A1C level is below 5.7 percent.
Can the A1C test be used to diagnose type 2 diabetes and prediabetes?
Yes. In 2009, an international expert committee recommended the A1C test as one of the tests available to help diagnose type 2 diabetes and prediabetes. 1Previously, only the traditional blood glucose tests were used to diagnose diabetes and prediabetes.
Because the A1C test does not require fasting and blood can be drawn for the test at any time of day, experts are hoping its convenience will allow more people to get tested—thus, decreasing the number of people with undiagnosed diabetes. However, some medical organizations continue to recommend using blood glucose tests for diagnosis.
1 The International Expert Committee. International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care. 2009;32(7):1327–1334.
Why should a person be tested for diabetes?
Testing is especially important because early in the disease diabetes has no symptoms. Although no test is perfect, the A1C and blood glucose tests are the best tools available to diagnose diabetes—a serious and lifelong disease.
Testing enables health care providers to find and treat diabetes before complications occur and to find and treat prediabetes, which can delay or prevent type 2 diabetes from developing.
Has the A1C test improved?
Yes. A1C laboratory tests are now standardized. In the past, the A1C test was not recommended for diagnosis of type 2 diabetes and prediabetes because the many different types of A1C tests could give varied results. The accuracy has been improved by the National Glycohemoglobin Standardization Program (NGSP), which developed standards for the A1C tests.
The NGSP certifies that manufacturers of A1C tests provide tests that are consistent with those used in a major diabetes study. The study established current A1C goals for blood glucose control that can reduce the occurrence of diabetes complications, such as blindness and blood vessel disease. 2
2 Nathan DM, Genuth S, Lachin J, et al. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The New England Journal of Medicine. 1993:329(14)977–986.
How is the A1C test used to diagnose type 2 diabetes and prediabetes?
The A1C test can be used to diagnose type 2 diabetes and prediabetes alone or in combination with other diabetes tests. When the A1C test is used for diagnosis, the blood sample must be sent to a laboratory that uses an NGSP-certified method for analysis to ensure the results are standardized.
Blood samples analyzed in a health care provider’s office, known as point-of-care (POC) tests, are not standardized for diagnosing diabetes. The following table provides the percentages that indicate diagnoses of normal, diabetes, and prediabetes according to A1C levels.
* Any test for diagnosis of diabetes requires confirmation with a second measurement unless there are clear symptoms of diabetes.
below 5.7 percent
6.5 percent or above
5.7 to 6.4 percent
Having prediabetes is a risk factor for getting type 2 diabetes. People with prediabetes may be retested each year. Within the prediabetes A1C range of 5.7 to 6.4 percent, the higher the A1C, the greater the risk of diabetes. Those with prediabetes are likely to develop type 2 diabetes within 10 years, but they can take steps to prevent or delay diabetes.
Is the A1C test used during pregnancy?
The A1C test may be used at the first visit to the health care provider during pregnancy to see if women with risk factors had undiagnosed diabetes before becoming pregnant. After that, the oral glucose tolerance test (OGTT) is used to test for diabetes that develops during pregnancy—known as gestational diabetes. After delivery, women who had gestational diabetes should be tested for persistent diabetes. Blood glucose tests, rather than the A1C test, should be used for testing within 12 weeks of delivery.
Can blood glucose tests still be used for diagnosing type 2 diabetes and prediabetes?
Yes. The standard blood glucose tests used for diagnosing type 2 diabetes and prediabetes-the fasting plasma glucose (FPG) test and the OGTT—are still recommended. The random plasma glucose test, also called the casual glucose test, may be used for diagnosing diabetes when symptoms of diabetes are present. In some cases, the A1C test is used to help health care providers confirm the results of a blood glucose test.
Can the A1C test result in a different diagnosis than the blood glucose tests?
Yes. In some people, a blood glucose test may indicate a diagnosis of diabetes while an A1C test does not. The reverse can also occur—an A1C test may indicate a diagnosis of diabetes even though a blood glucose test does not. Because of these variations in test results, health care providers repeat tests before making a diagnosis.
People with differing test results may be in an early stage of the disease, where blood glucose levels have not risen high enough to show on every test. Sometimes, making simple changes in lifestyle—losing a small amount of weight and increasing physical activity—can help people in this early stage reverse diabetes or delay its onset.
Are diabetes blood test results always accurate?
All laboratory test results can vary from day to day and from test to test. Results can vary
within the person being tested. A person’s blood glucose levels normally move up and down depending on meals, exercise, sickness, and stress.
between different tests. Each test measures blood glucose levels in a different way. For example, the FPG test measures glucose that is floating free in the blood after fasting and only shows the blood glucose level at the time of the test. Repeated blood glucose tests, such as self-monitoring several times a day with a home meter, can record the natural variations of blood glucose levels during the day. The A1C test represents the amount of glucose attached to hemoglobin, so it reflects an average of all the blood glucose levels a person may experience over 3 months. The A1C test will not show day-to-day changes.
The following chart shows how multiple blood glucose measurements over 4 days compare with an A1C measurement.
Blood Glucose Measurements Compared with A1C Measurements Over 4 Days
The straight black line indicates an A1C measurement of 7.0 percent. The blue line shows blood glucose test results from self-monitoring four times a day over a 4-day period.
within the same test. Even when the same blood sample is repeatedly measured in the same laboratory, the results may vary due to small changes in temperature, equipment, or sample handling.
Health care providers take these variations into account when considering test results and repeat laboratory tests for confirmation. Diabetes develops over time, so even with variations in test results, health care providers can tell when overall blood glucose levels are becoming too high.
Comparing test results from different laboratories can be misleading. People should consider requesting new laboratory tests when they change health care providers, or if their health care provider’s office changes the laboratory or clinic it uses for blood testing.
How accurate is the A1C test?
The A1C test result can be up to 0.5 percent higher or lower than the actual percentage. This means an A1C measured as 7.0 percent could indicate a true A1C anywhere in the range from ~6.5 to 7.5 percent.
The drawing below illustrates the range of possible true values when an A1C is 7.0 percent on the lab report. This range is based on the inherent variability of the laboratory test, often referred to as the coefficient of variation. Different degrees of laboratory variability result in different ranges of possible true values. The range illustrated is the maximum allowed by test methods approved by NGSP.
To put the A1C test into perspective, an FPG test result of 126 mg/dL obtained from a laboratory test accounting for typical variability within an individual person could indicate a true FPG anywhere in the range from ~110 to 142 mg/dL. This variation will be even greater if the blood sample is not processed promptly or is not put on ice, causing blood glucose levels in the sample to decrease. The drawing below illustrates the range of possible true values for an FPG of 126 mg/dL.
Can the A1C test give false results?
Yes, for some people. The A1C test can be unreliable for diagnosing or monitoring diabetes in people with certain conditions that are known to interfere with the results. Interference should be suspected when A1C results seem very different from the results of a blood glucose test.
People of African, Mediterranean, or Southeast Asian descent, or people with family members with sickle cell anemia or a thalassemia are particularly at risk of interference. People in these groups may have a less common type of hemoglobin, known as a hemoglobin variant, that can interfere with some A1C tests. Most people with a hemoglobin variant have no symptoms and may not know that they carry this type of hemoglobin.
Not all of the A1C tests are unreliable for people with a hemoglobin variant. People with false results from one type of A1C test may need a different type of A1C test for measuring their average blood glucose level. The NGSP provides information for health care providers about which A1C tests are appropriate to use for specific hemoglobin variants at www.ngsp.org .
More information about problems with the A1C test and different forms of sickle cell anemia is provided in the NIDDK health topics:
False A1C results may also occur in people with other problems that affect their blood or hemoglobin. For example, a falsely low A1C result can occur in people with
A falsely elevated A1C result can occur in people who
are very low in iron, for example, those with iron deficiency anemia
Other causes of false A1C results include
How is the A1C test used after diagnosis of diabetes?
Health care providers can use the A1C test to monitor blood glucose levels in people with type 1 or type 2 diabetes. The A1C test is not used to monitor gestational diabetes.
The American Diabetes Association recommends that people with diabetes who are meeting treatment goals and have stable blood glucose levels have the A1C test twice a year. Health care providers may repeat the A1C test as often as four times a year until blood glucose levels reach recommended levels.
The A1C test helps health care providers adjust medication to reduce the risk of long-term diabetes complications. Studies have demonstrated substantial reductions in long-term complications with the lowering of A1C levels.
When the A1C test is used for monitoring blood glucose levels in a person with diabetes, the blood sample can be analyzed in a health care provider’s office using a POC test to give immediate results. However, POC tests are less reliable and not as accurate as most laboratory tests.
How does the A1C relate to estimated average glucose?
Estimated average glucose (eAG) is calculated from the A1C. Some laboratories report eAG with the A1C test results. The eAG number helps people with diabetes relate their A1C to daily glucose monitoring levels. The eAG calculation converts the A1C percentage to the same units used by home glucose meters—milligrams per deciliter (mg/dL).
The eAG number will not match daily glucose readings because it is a long-term average rather than the blood glucose level at a single time, as measured with the home glucose meter. The following table shows the relationship between the A1C and the eAG.
Relationship between A1C and eAG
Source: Adapted from American Diabetes Association. Standards of medical care in diabetes—2014. Diabetes Care. 2014;37(Supp 1):S14–S80, table 8.
What A1C target should people have?
People will have different A1C targets depending on their diabetes history and their general health. People should discuss their A1C target with their health care provider. Studies have shown that people with diabetes can reduce the risk of diabetes complications by keeping A1C levels below 7 percent.
Maintaining good blood glucose control will benefit those with new-onset diabetes for many years to come. However, an A1C level that is safe for one person may not be safe for another. For example, keeping an A1C level below 7 percent may not be safe if it leads to problems with hypoglycemia, also called low blood glucose.
Less strict blood glucose control, or an A1C between 7 and 8 percent—or even higher in some circumstances—may be appropriate in people who have
long-standing diabetes and difficulty attaining a lower goal
advanced diabetes complications such as chronic kidney disease, nerve problems, or cardiovascular disease
Will the A1C test show changes in blood glucose levels?
Large changes in a person’s blood glucose levels over the past month will show up in their A1C test result, but the A1C does not show sudden, temporary increases or decreases in blood glucose levels. Even though the A1C represents a long-term average, blood glucose levels within the past 30 days have a greater effect on the A1C reading than those in previous months.
Points to Remember
The A1C test is a blood test that provides information about a person’s average levels of blood glucose, also called blood sugar, over the past 3 months.
The A1C test is based on the attachment of glucose to hemoglobin, the protein in red blood cells that carries oxygen. Thus, the A1C test reflects the average of a person’s blood glucose levels over the past 3 months.
In 2009, an international expert committee recommended the A1C test be used as one of the tests available to help diagnose type 2 diabetes and prediabetes.
Because the A1C test does not require fasting and blood can be drawn for the test at any time of day, experts are hoping its convenience will allow more people to get tested—thus, decreasing the number of people with undiagnosed diabetes.
In the past, the A1C test was not recommended for diagnosis of type 2 diabetes and prediabetes because the many different types of A1C tests could give varied results. The accuracy has been improved by the National Glycohemoglobin Standardization Program (NGSP), which developed standards for the A1C tests. Blood samples analyzed in a health care provider’s office, known as point-of-care (POC) tests, are not standardized for use in diagnosing diabetes.
The A1C test may be used at the first visit to the health care provider during pregnancy to see if women with risk factors had undiagnosed diabetes before becoming pregnant. After that, the oral glucose tolerance test (OGTT) is used to test for diabetes that develops during pregnancy—known as gestational diabetes.
The standard blood glucose tests used for diagnosing type 2 diabetes and prediabetes—the fasting plasma glucose (FPG) test and the OGTT—are still recommended. The random plasma glucose test may be used for diagnosing diabetes when symptoms of diabetes are present.
The A1C test can be unreliable for diagnosing or monitoring diabetes in people with certain conditions that are known to interfere with the results.
The American Diabetes Association recommends that people with diabetes who are meeting treatment goals and have stable blood glucose levels have the A1C test twice a year.
Estimated average glucose (eAG) is calculated from the A1C to help people with diabetes relate their A1C to daily glucose monitoring levels.
People will have different A1C targets depending on their diabetes history and their general health. People should discuss their A1C target with their health care provider.
Diabetes is a group of chronic diseases that affect metabolism—the way the body uses food for energy and growth. Millions of people have diabetes, which can lead to serious health problems if it is not managed well. Conventional medical treatments and following a healthy lifestyle, including watching your weight, can help you prevent, manage, and control many complications of diabetes. Researchers are studying several complementary health approaches, including dietary supplements, to see if they can help people manage type 2 diabetes or lower their risk of developing the disease; however, there is currently not enough scientific evidence to suggest that any dietary supplements can help prevent or manage type 2 diabetes.
Here are 6 things you should know about taking dietary supplements for type 2 diabetes.
A healthy diet, physical activity, and blood glucose testing are the basic tools for managing type 2 diabetes. Your health care providers will help you learn to manage your diabetes and track how well you are controlling it. It is critical not to replace proven conventional medical treatment for diabetes with an unproven health product or practice.
Some dietary supplements may have side effects, including interacting with your diabetes treatment or increasing your risk of kidney problems. This is of particular concern because diabetes is the leading cause of chronic kidney disease and kidney failure in the United States. Supplement use should be monitored closely in patients who have or are at risk for kidney disease.
Chromium (an essential trace mineral found in many foods) has been studied for preventing diabetes and controlling glucose levels, but research has found it has few or no benefits. There have been a few reports of kidney damage, muscular problems, and skin reactions following large doses of chromium.
There is no evidence that magnesium helps to manage diabetes; however, research suggests that people with lower magnesium intake may have a greater risk of developing diabetes. A large 2007 study found an association between a higher intake of cereal fiber and magnesium and a reduced risk of developing type 2 diabetes. Large doses of magnesium in supplements can cause diarrhea and abdominal cramping, and enormous doses—more than 5,000 mg/day per day—can be deadly.
There is no substantial evidence that herbs and other dietary supplements, including cinnamon and omega-3s, can help to control diabetes or its complications. Researchers have found some risks but no clear benefits of cinnamon for people with diabetes. For example, a 2012 review of the scientific literature did not support using cinnamon for type 1 or type 2 diabetes.
Talk with your health care provider before considering any dietary supplement for yourself, particularly if you are pregnant or nursing, or for a child. Do not replace scientifically proven treatments for diabetes with unproven health products or practices. The consequences of not following your prescribed medical regimen for diabetes can be very serious.
When medicines and lifestyle changes are not enough to manage your diabetes, a less common treatment may be an option. Other treatments include bariatric surgery for certain people with type 1 or type 2 diabetes, and an “artificial pancreas” and pancreatic islet transplantation for some people with type 1 diabetes.
Also called weight-loss surgery or metabolic surgery, bariatric surgery may help some people with obesity and type 2 diabetes lose a large amount of weight and regain normal blood glucose levels. Some people with diabetes may no longer need their diabetes medicine after bariatric surgery. Whether and for how long blood glucose levels improve seems to vary by the patient, type of weight-loss surgery, and amount of weight the person loses. Other factors include how long someone has had diabetes and whether or not the person uses insulin.1
Recent research suggests that weight-loss surgery also may help improve blood glucose control in people with type 1 diabetes who are obese.2
Researchers are studying the long-term results of bariatric surgery in people with type 1 and type 2 diabetes.
The NIDDK has played an important role in developing “artificial pancreas” technology. An artificial pancreas replaces manual blood glucose testing and the use of insulin shots or a pump. A single system monitors blood glucose levels around the clock and provides insulin or a combination of insulin and a second hormone, glucagon, automatically. The system can also be monitored remotely, for example by parents or medical staff.
In 2016, the FDA approved a type of artificial pancreas system called a hybrid closed-loop system. This system tests your glucose level every 5 minutes throughout the day and night, and automatically gives you the right amount of insulin.
You still need to manually adjust the amount of insulin the pump delivers at mealtimes. But, the artificial pancreas may free you from some of the daily tasks needed to keep your blood glucose stable—or help you sleep through the night without the need to wake and test your glucose or take medicine.
The hybrid closed-loop system is expected to be available in the U.S. in 2017. Talk with your health care provider about whether this system might be right for you.
The NIDDK has funded several important studies on different types of artificial pancreas devices to help better people with type 1 diabetes manage their disease. The devices may also help people with type 2 diabetes and gestational diabetes.
Pancreatic islet transplantation
Pancreatic islet transplantation is an experimental treatment for poorly controlled type 1 diabetes. Pancreatic islets are clusters of cells in the pancreas that make the hormone insulin. In type 1 diabetes, the body’s immune system attacks these cells. A pancreatic islet transplant replaces destroyed islets with new ones that make and release insulin. This procedure takes islets from the pancreas of an organ donor and transfers them to a person with type 1 diabetes. Because researchers are still studying pancreatic islet transplantation, the procedure is only available to people enrolled in research studies. Learn more about islet transplantation studies.