When “Tired Blood” is Slowing You Down

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Most people have heard of anemia and know that it has something to do with the blood. Most people also associate anemia with feeling tired. But probably not too many people could explain exactly what anemia is.

Stated simply, anemia is a condition in which there is a lower than normal number of healthy red blood cells in the body and/or a lower than normal amount of hemoglobin in the red blood cells.

Red blood cells carry oxygen from your lungs to the rest of your body. The specific part of the red blood cell that carries oxygen is called hemoglobin. Red blood cells also carry waste products from the cells to the urinary and respiratory systems to be excreted. When either the number of red blood cells or the amount of hemoglobin is low, the body’s cells receive less oxygen than normal. A low oxygen level can cause fatigue and other symptoms such as weakness, difficulty exercising, and light-headedness.

Anemia can develop for many reasons. In fact, there are more than 400 types of anemia. But they can all be categorized into these three general groups:

    • Anemia caused by the loss of blood


    • Anemia caused by a decrease in red blood cell production in the bone marrow or impaired production of red blood cells


  • Anemia caused by red blood cell destruction

Anemia is a fairly common condition, but it often goes unrecognized and therefore not treated. Its symptoms are vague and easily mistaken for symptoms of other serious or chronic diseases. But even mild anemia can significantly lower one’s quality of life, and untreated anemia can have serious long-term health effects.

Diabetes and anemia

Diabetes does not directly cause anemia, but certain complications and conditions associated with diabetes can contribute to it. For example, both diabetes-related kidney disease (nephropathy) and nerve damage (neuropathy) can contribute to the development of anemia. In addition, taking certain oral diabetes drugs can raise the risk of developing anemia. People with diabetes can also have anemia as a result of not eating well or of having a condition that interferes with the absorption of nutrients.

Kidney disease. Normally, the kidneys secrete a hormone called erythropoietin, which stimulates the bone marrow to produce red blood cells. In diabetic nephropathy, the tiny blood vessels that filter waste products from the body become damaged and start “leaking” substances (such as protein) into the urine. At the same time, the amount of erythropoietin produced by the kidneys is reduced, leading to anemia. Some studies have shown that reduced erythropoietin production and anemia happen earlier in people with diabetes and kidney disease than in those with kidney disease and no diabetes.

Both chronically high blood glucose levels and high blood pressure can cause kidney damage.

Neuropathy. In people who have a type of neuropathy called autonomic neuropathy, the body may not be able to properly signal the kidneys to produce more erythropoietin in response to anemia.

Heart failure. People who have diabetes are at increased risk for heart failure, or the inability of the heart to pump adequate blood to meet the body’s needs. Decreased heart function can cause kidney dysfunction, and many people with heart failure also have nutritional deficiencies; both of these can contribute to anemia. About 20% of people with heart failure are anemic.

Nutrient deficiencies. Many people who have diabetes have nutrient deficiencies that can cause anemia. Nutrient deficiencies can be caused by either not eating enough nutrients (because a person restricts his food choices, for example) or by the body’s inability to absorb the nutrients that are eaten. Deficiencies in iron, vitamin B12, vitamin B6, and folate can all cause anemia.

One condition that affects the body’s ability to absorb nutrients is celiac disease. In celiac disease, the body cannot tolerate gluten, a protein found in wheat, barley, and rye. If gluten is eaten, the normal, fingerlike folds of the small intestine flatten out, preventing the absorption of not just the gluten but of other nutrients, as well. About one in 20 people who have diabetes also have celiac disease.

Bariatric (weight-loss) surgery can also lead to nutrient deficiencies that cause anemia. Vitamin and mineral supplements are generally needed after bariatric surgery to prevent this.

Diabetes drugs. Metformin is the most widely prescribed treatment for people with Type 2 diabetes. It is now recognized that metformin can cause malabsorption of vitamin B12 and that long-term use (12–15 years) of metformin leads to vitamin B12 deficiency in 30% of people who use it. Vitamin B12 deficiency can cause anemia and also peripheral neuropathy (nerve damage in the feet, legs, hands, and arms).

Another type of diabetes drug, the thiazolidinediones, which include pioglitazone (Actos) and rosiglitazone (Avandia), can also cause mild anemia by slightly decreasing hemoglobin levels and hematocrit, a measurement of the proportion of blood that is made up of red blood cells.


A person with very mild anemia may have no symptoms, but more serious anemia can cause tiredness, weakness, dizziness, irritability, shortness of breath, and/or depression. It can also cause brittle nails; pale skin; cold hands and feet; numbness and/or tingling in the fingers, toes, and feet; chest pain; an irregular heartbeat; cravings to eat unusual things such as ice; difficulty concentrating; and sexual problems.

If you have these symptoms, ask your health-care provider to check to see if you are anemic.

Diagnosing anemia

Anemia is diagnosed with a blood test. The blood sample is analyzed for the amount of hemoglobin in the blood and for the hematocrit.

For men, the normal hemoglobin range is 13.8–;17.2 grams per deciliter (g/dl), and the normal hematocrit is 40.7% to 50.3%.

For women who are not pregnant, the normal hemoglobin range is 12.1–15.1 gm/dl, and the normal hematocrit is 36.1% to 44.3%.

The normal ranges for both men and women may vary somewhat from one laboratory to another and also vary according to altitude. At higher altitudes, the body produces more red blood cells in response to the decreased oxygen available. A higher number of red blood cells means that hemoglobin levels and hematocrit are also increased.

Test results below the low end of the normal range for either hemoglobin or hematocrit can indicate anemia. If initial tests show anemia, more blood tests may be done to establish the cause of the anemia and the best approach to treatment. For example, a test for the level of iron in the blood is often done, since iron deficiency is the most common cause of anemia. Other diagnostic tools include a physical examination and asking about such things as family history of anemia, diet, use of prescription or over-the-counter drugs, heavy menstrual bleeding (in premenopausal women), and any signs of internal bleeding, such as blood in stools.

As a side note, blood glucose meters have a hematocrit range at which they give accurate results. Having a hematocrit that falls outside your meter’s range may mean you are getting inaccurate results when monitoring your blood glucose. The package insert that came with your meter should state its hematocrit range.

Treatment and prevention

The treatment for anemia depends on the cause and severity of it. For example, if anemia is due to blood loss and it’s not severe, identifying the source of bleeding and stopping it will often be enough to reverse the anemia. For other causes or more serious cases, other steps may need to be taken, such as treating an underlying disease, taking vitamin or mineral supplements, and making dietary changes.

In all cases, it takes time for the body to create new, healthy red blood cells, so a person is likely to feel better gradually.

Because anemia can recur, depending on the cause, the steps taken to treat it may need to be continued — possibly for life — to prevent it from coming back.

Kidney disease. If you have kidney problems, you should be under the care of a nephrologist, a physician who specializes in kidney diseases. Treatment for anemia related to kidney disease may include both steps to reverse the anemia and steps to improve kidney function (or prevent it from worsening). For example, to reverse the anemia, injections of a type of drug called an erythropoiesis-stimulating agent may be prescribed to stimulate your bone marrow to produce red blood cells. In addition, drug therapy with certain types of blood pressure drugs may be prescribed to prevent further kidney damage.

Also important for preventing further kidney damage are attaining and maintaining blood glucose levels as near to normal as possible and a blood pressure level below 130/80 mm Hg. If your kidney damage is already severe, however, you may need dialysis or a kidney transplant.

No matter how severe your kidney disease, you should meet with a registered dietitian who specializes in kidney diseases to help you with your food choices. People with diabetes and kidney disease have dietary needs that are somewhat different from those of people who have diabetes and no kidney disease. In particular, they need individualized guidelines for protein, potassium, phosphorus, and fluid intake, as well as for carbohydrate intake.

Heart failure. Take your medicines as prescribed, and follow your healthy lifestyle plan. Weigh yourself every morning, and report a weight gain of 3 pounds in one day or 5 pounds in one week to your health-care team. Rapid weight gain such as this can mean that your heart function is worsening, and fluid is accumulating somewhere in your body.

Diabetes drugs. If you take either metformin or a thiazolidinedione (Actos or Avandia), ask your health-care provider to check your blood to see if you are anemic. If your lab results show a low vitamin B12 level, you may be prescribed B12 supplementation. If your hematocrit and hemoglobin are low, your dose of Actos or Avandia may reduced, you may be advised to eat more foods that are higher in iron, and/or you may be advised to start taking iron supplements.

Nutrient deficiencies. If your anemia is due to blood loss or a nutrient deficiency, you may be instructed to eat more iron-rich foods and possibly to take iron supplements.

Iron-rich foods include beef, organ meats, pork, poultry, fish, clams, and oysters. The iron in foods of animal origin such as these is usually easily absorbed by the body. The iron in plant foods, such as fruits, vegetables, dried beans, nuts, and grain products, is less easily absorbed, but absorption can be increased by eating these foods along with foods high in vitamin C, such as dark leafy greens, broccoli, bell peppers (particularly red, yellow, and orange peppers), tomatoes, mangoes, papayas, and kiwifruits.

Taking vitamin C supplements is another option for helping your body absorb iron. However, vitamin C supplements can affect the accuracy of some blood glucose meters. Before you take vitamin C supplements, ask your meter’s manufacturer if taking vitamin C (also called ascorbic acid) affects the performance of your meter.

If your nutrient deficiency is due to a lack of vitamins or minerals other than iron, such as folate or vitamin B12, you may be prescribed a supplement, and you will be encouraged to eat foods high in folate and B12.

Foods high in folate include green leafy vegetables, eggs, seafood, lean beef, organ meats, orange juice, dry beans, lentils, asparagus, and broccoli.

Foods high in vitamin B12 include all animal products, including eggs, dairy products, and meat. People who follow a vegan diet are at risk of vitamin B12 deficiency and should take a vitamin B12 supplement.

If your nutrient deficiency is found to be a consequence of having celiac disease, you will need to follow a strictly gluten-free diet for the rest of your life to allow your small intestine to heal and remain healthy.

Anyone diagnosed with a nutrient deficiency should meet with a registered dietitian or nutritionist to discuss healthy food choices and how to prevent such a deficiency from happening again. Meeting with a dietitian may be particularly helpful for people diagnosed with celiac disease, since switching to a gluten-free diet can be a challenge.

Feeling better

As many as 25% of Americans with diabetes also have anemia, so if you feel fatigued or weak, get it checked out. Don’t diagnose yourself with anemia, however. There are many reasons you might feel tired and weak, and trying to treat yourself for anemia when you don’t have it could create or worsen other problems.

If your doctor does diagnose you with anemia and prescribes a treatment, you should get regular blood tests to track your progress. In time you should notice that you feel much better.


For a listing of anemia organizations and resources, see “Anemia Resources.”

Originally Published September 6, 2011

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