Anemia is defined as a low red blood cell count or low hemoglobin concentration, though other indications in a CBC (Complete Blood Count) can also suggest this, including the MCV (mean corpuscular volume) and MCH (mean corpuscular hemoglobin) levels. If the MCV and/or MCH are high, it indicates macrocytic anemia, usually caused by either low B12 or low folate. If MCV and/or MCH are low, it indicates iron deficiency anemia.

Symptoms of Anemia

Symptoms of either type of anemia include: 

  • Fatigue
  • A rapid heart beat (tachycardia)
  • Palpitations
  • Shortness of breath
  • Headache
  • Dizziness
  • Pale skin
  • Leg cramps
  • Difficulty concentrating.

The Diabetes and Iron Deficiency Anemia Connection

It’s common to see elevation of ferritin, the storage form of iron, in cases of insulin resistance and diabetes. This is because ferritin is also considered an acute phase reactant, which means it spikes in the presence of inflammation. Ferritin is primarily stored in the liver, and it’s common for it to elevate in cases of fatty liver disease, which is strongly connected to insulin resistance.

However, serum iron levels tend to fall in diabetic patients—there’s an inverse correlation between iron levels and HbA1c (a measurement of where the glucose has been over the last 3 months). There are several possible reasons for this.

  1. Kidney complications. Elevated blood sugar will, over time, damage the tiny blood vessels in the kidneys in the same way that it can damage the vessels anywhere else (leading to cardiovascular disease). Smaller vessels show damage first, which is why kidney damage is one of the “side effects” of diabetes to watch out for. The significance here: the kidneys produce the hormone erythropoietin, which tells bone marrow to make more red blood cells. Underperforming kidneys will also decrease production of erythropoietin, leading to anemia. This study shows that diabetics with reduced renal function are more likely to end up with iron deficiency anemia than those with without reduced renal function.
  2. Neuropathy. Prolonged elevation of blood sugar can also damage nerves, probably because nerves also require a blood supply, which they receive from tiny arteries. There are several types of neuropathy that can result, one of which is autonomic neuropathy. Unlike the typical symptoms of peripheral neuropathy (tingling and numbness of fingers and toes), this can present with dizziness, fainting, digestive disturbances, sexual dysfunction—and anemia, because the nerves supplying the kidneys are also deficient, thus resulting in lower erythropoietin production.
  3. Malabsorption. Diabetes is often associated with malabsorption of nutrients, including iron. Often this manifests as diarrhea, which may also go back to autonomic neuropathy.

The Diabetes and Macrocytic Anemia Connection

Malabsorption can certainly decrease all nutrients, including B12 and folate, which can result in macrocytic anemia. But the more common cause of this kind of anemia in diabetes is Metformin. Between 10-30% of people taking Metformin will experience B12 deficiency.

The Upshot

If you are diabetic or even pre-diabetic, make sure you ask your doctor to check your serum B12 (if you’re not taking B12—if you are, it will be very high and won’t tell you much), your ferritin, and your serum iron and TIBC (total iron binding capacity). This is particularly important if you struggle with any of the symptoms of anemia and have yet to find a cause.