I. Introduction

According to the Diabetes Research Institute, nearly 10% of the U.S. population has some form of diabetes. Type 2 diabetes, which develops when an individual lacks insulin or can’t use insulin effectively, is the most common. Insulin is a hormone that carries glucose into the cells so that it doesn’t build up in the bloodstream. Kidney disease is even more common, affecting around 15% of the adult population of the United States. Iron-deficiency anemia affects 2% of adult males and anywhere from 9% to 20% of females in the United States.

This guide provides an overview of the hemoglobin A1c test, including an explanation of why it is done. It also contains in-depth information on Type 2 diabetes, kidney disease, and iron-deficiency anemia.

II. Overview of the Hemoglobin A1c Test

Why should I get tested?

The purpose of the A1c test is to measure the amount of glycated hemoglobin in a person’s blood. Type 2 diabetes, if left untreated, can lead to serious complications, including high blood pressure and stroke. Having the test can help diagnose diabetes as early as possible, reducing the risk of complications and improving the quality of life for someone with the condition. The A1c test can also be used in the diagnosis and management of kidney disease and iron-deficiency anemia. Both conditions can cause severe symptoms; therefore, having the test completed can help healthcare providers develop an appropriate treatment plan before the symptoms become unmanageable.

When should I get tested?

According to the CDC, all adults should have the A1c test once they have turned 45. If the test is needed again in the future, the result can be compared to this initial result to determine if the individual’s condition has worsened or stayed the same. Adults under the age of 45 should have the A1c test if they are overweight or have other risk factors for diabetes or prediabetes.

What is required for the test?

The A1c test is performed on a blood sample.

How do I prepare for the test?

Unlike the blood glucose test, the A1c test is not affected by foods and beverages; therefore, no special preparation is required.

III. The Basics of Diabetes, Iron-Deficiency Anemia, and Kidney Disease


In the human body, some cells rely on glucose as a source of energy. Insulin helps glucose enter these cells, regulating the amount of glucose left to circulate in the bloodstream. In individuals with Type 2 diabetes, there isn’t enough insulin, or the body is resistant to the effects of insulin, causing the amount of glucose in the blood to increase. Excess glucose damages the blood vessels, increasing the risk of nerve damage, kidney disease, stroke, high blood pressure, and other complications.

Some people are more likely to develop Type 2 diabetes than others. One of the key risk factors is excess weight; therefore, individuals with obesity have a higher risk of developing this condition. People who don’t engage in much exercise and individuals whose family members have Type 2 diabetes also have an increased risk.

At first, Type 2 diabetes may not cause any symptoms. As glucose levels increase, however, an individual is likely to experience symptoms, such as fatigue, unintended weight loss, slow healing wounds, urinary frequency, excessive thirst, and extreme hunger.

Iron-Deficiency Anemia

Iron is an important mineral involved in the production of hemoglobin, which is the part of the red blood cell that carries oxygen. Without enough hemoglobin, the blood doesn’t deliver the right amount of oxygen to the body’s cells and tissues. Several risk factors increase the risk of developing iron-deficiency anemia, including heavy menstrual periods, peptic ulcer disease, recent trauma, and a lack of iron-rich foods in the diet. Individuals with a history of gastric bypass may develop iron-deficiency anemia due to an impaired ability to absorb iron from foods and beverages. Crohn’s disease and other disorders of the digestive system can also affect iron absorption, leading to iron-deficiency anemia.

Symptoms of iron-deficiency anemia include fatigue, chest pain, shortness of breath, weakness, activity, and pale skin. Some of these symptoms may become worse while engaging in physical activity.

Kidney Disease

Most humans are born with two kidneys, which are bean-shaped organs that filter the blood and produce several substances the body needs to function normally. In people with kidney disease, something damages the kidneys, preventing them from carrying out these important functions. If the kidneys can’t filter the blood properly, fluid and waste products can build up, causing an individual with kidney disease to feel sick or fatigued. Some people with kidney disease develop hyperparathyroidism because the kidneys can’t help maintain a normal balance of calcium, vitamin D, and phosphorus in the body. Hyperparathyroidism is a condition in which a person has too much parathyroid hormone (PTH). This hormone plays an important role in maintaining normal calcium levels.

Chronic kidney disease has several potential causes, but high blood pressure and diabetes are the most common. Both conditions can damage the blood vessels, making the kidneys less effective at filtering waste and maintaining normal fluid levels. In addition to high blood pressure and diabetes, kidney disease may be caused by the following:

  • Infections
  • Lupus and other autoimmune disorders
  • Lead (or another heavy metal) poisoning
  • Medications that damage the kidneys
  • Narrowing of the renal artery
  • Polycystic kidney disease
  • Rare genetic disorders

Kidney disease doesn’t always cause symptoms in its early stages. As it progresses, kidney disease may cause symptoms, such as changes in urinary frequency, dry skin, itchy skin, weight loss, difficulty sleeping, vomiting, fatigue, headache, and muscle cramps.

IV. How a Hemoglobin A1c Test Works

The hemoglobin A1c test requires a small sample of blood. This sample is typically collected by a technician working in a doctor’s office, outpatient laboratory, hospital, or medical clinic. To collect the blood, the technician performs a venipuncture, which literally means to puncture a vein. This procedure involves finding a viable vein in the individual’s arm or hand, swabbing the area with antiseptic to reduce the risk of infection, and using a needle to draw blood out of the vein. When the sample arrives at the laboratory, it’s diluted and run through a glycohemoglobin analyzer to determine how much glycated hemoglobin is present.

V. Treatment for Diabetes, Iron-Deficiency Anemia, and Kidney Disease


The right approach to treating Type 2 diabetes depends on several factors, including an individual’s health history and current A1c level. Therefore, it’s important to consult a physician or other licensed medical professional before making any lifestyle changes that could affect glucose and A1c levels. Following a diabetic diet and getting enough exercise are two of the most important actions a diabetic can take to manage this condition. Glucose levels tend to increase when an individual eats sugary foods and other foods with high levels of carbohydrates. Eating roughly the same amount of carbs at each meal can help diabetics prevent dangerous glucose spikes. Getting plenty of exercise can also reduce glucose levels by helping the body use insulin more effectively.

Lifestyle changes are beneficial, but they aren’t always enough to keep glucose levels under control. Some people with Type 2 diabetes have to take metformin, a medication that reduces glucose levels in two ways. First, metformin tells the liver to stop making so much glucose. Second, it increases the body’s sensitivity to insulin, which helps the insulin work better. If metformin or another oral medication doesn’t work, the individual may also need to take insulin injections each day.

Iron-Deficiency Anemia

Healthcare providers develop treatment plans for people with iron-deficiency anemia based on the underlying cause of the anemia. For people who have iron-deficiency anemia because they don’t have enough iron in their diets, eating more iron-rich foods and taking iron supplements can help replenish iron levels. Individuals with severe iron deficiencies may need to have iron therapy or transfusions of red blood cells. Iron therapy involves delivering iron directly into the bloodstream via an IV line. RBC transfusions cause a rapid increase in the number of RBCs in the blood, which can help people with iron-deficiency anemia feel better by increasing the amount of hemoglobin in the blood. If the iron deficiency is caused by some type of internal bleeding, such as bleeding from an ulcer, the individual may need surgery to treat the underlying cause of the bleeding.

Kidney Disease

Medications and lifestyle changes are the main treatments for kidney disease. Both can prevent kidney disease from progressing from an early stage to a later stage. Some people with kidney disease take medications to control their blood pressure or eliminate excess fluid from the body. Medications may also be used to reduce cholesterol levels or keep glucose levels under control.

It’s also important to work with a dietitian to develop a diet plan that provides an adequate amount of nutrients without making kidney disease worse. When the kidneys don’t work properly, minerals can build up in the blood, increasing the risk of complications. These minerals include sodium and potassium. A renal diet restricts the intake of foods and beverages containing high levels of sodium and potassium, which can prevent swelling, fatigue, and other symptoms from becoming worse.

If kidney disease progresses to kidney failure, it may be necessary for an individual to have hemodialysis. During this procedure, blood is removed from the individual’s bloodstream. It flows into a dialyzer, which is a mechanical filter that acts like an artificial kidney. The dialyzer cleans the blood by removing excess minerals, fluid, and waste products. Once the blood has been cleaned, it is returned to the bloodstream. Removing excess fluid and wastes from the blood can help someone with kidney disease feel less weak and fatigued, but it’s not a cure for kidney disease.


What is a normal hemoglobin A1c level?

A normal A1c level is less than 5.7%.

What are some other causes of an abnormal A1c level?

Liver disease can cause a false elevation of an individual’s A1c level. This means that the individual’s A1c is high, even though his or her glucose levels have been normal over the past three months.

My doctor says I have prediabetes. What does that mean?

Prediabetes is a condition characterized by an A1c of 5.7% to 6.4%. It’s not full-blown diabetes, but it does increase the risk of developing diabetes. An individual diagnosed with prediabetes should take steps to reduce glucose levels, which can prevent Type 2 diabetes and help the individual avoid complications of diabetes in the future.

If my A1c level is high, will I need other tests?

An individual with an elevated A1c may need a second A1c test to confirm the abnormal result. The individual may also need to have regular glucose tests to determine if prediabetes is progressing to diabetes or if treatments for diabetes are working as intended.

How can I keep my A1c from going higher?

An individual’s A1c level is an estimate of his or her average glucose levels over a period of three months. To reduce a high A1c level, it’s necessary to reduce overall glucose levels. This can be accomplished by following a diabetic diet, getting plenty of exercise, and taking medications as prescribed by a health professional. If oral medications don’t work, insulin injections can prevent glucose levels from increasing, which can reduce the A1c level. In people with liver disease, which causes a false elevation of A1c, these changes may not affect the results of subsequent A1c tests.

VII. Additional Resources

For more information on diabetes, iron-deficiency anemia, and kidney disease, along with the tests used to diagnose and monitor people with these conditions, visit these resources.

Name Website Summary
American Diabetes Association www.diabetes.org Find tips for managing diabetes.
National Kidney Foundation www.kidney.org Learn more about kidney failure and other conditions that affect the kidneys.
American Kidney Fund www.kidneyfund.org Access resources designed for people living with kidney disease and kidney failure.
National Institute of Diabetes and Digestive and Kidney Diseases www.niddk.nih.gov The NIDDK offers comprehensive articles on kidney failure and diabetes.
Diabetes Research Institute www.diabetesresearch.org DRI funds research into diabetes treatments and offers educational materials on managing diabetes.

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