Anemia affects roughly one in three people with type 2 diabetes, a rate far higher than in the general population, and the relationship between the two conditions runs in both directions. Diabetes damages organs and disrupts processes that the body needs to produce and maintain healthy red blood cells, while anemia, in turn, distorts one of the most widely used tools for monitoring blood sugar. Understanding how these conditions feed into each other changes how you and your doctor should approach screening, treatment, and even the interpretation of routine lab results.
How Common Is Anemia in People With Diabetes
A study of more than 19,000 patients with type 2 diabetes found that about 30% were anemic. The rates were uneven: roughly 22% of diabetic men had anemia compared with nearly 39% of diabetic women. Blood sugar control mattered too. Among patients whose diabetes was well managed, about 28% were anemic, while the figure rose to about 33% in those with poor glycemic control.1PubMed Central. Prevalence of Anemia in Type 2 Diabetic Patients These numbers are striking when you consider that anemia prevalence in the overall adult population is typically much lower. The International Diabetes Federation’s Southeast Asian Region has issued a position statement calling for routine anemia screening in all patients with diabetes, arguing that catching it early improves clinical outcomes.2PubMed. Diabetes and Anemia: International Diabetes Federation (IDF) – Southeast Asian Region (SEAR) position statement
Why Diabetes Causes Anemia
There is no single mechanism. Diabetes chips away at red blood cell production and survival through several independent pathways, which is part of why the anemia it causes can be tricky to diagnose and treat. The main culprits are kidney damage, chronic inflammation, direct harm to red blood cells from high blood sugar, and medication side effects.
Kidney Damage and Erythropoietin Loss
Your kidneys produce erythropoietin, the hormone that tells bone marrow to make new red blood cells. In early diabetic kidney disease, the specialized cells that manufacture erythropoietin can be damaged before you lose any measurable kidney filtration.3Journal of Diabetes and its Complications. Anemia and the role of erythropoietin in diabetes This means a person with diabetes can develop anemia from erythropoietin deficiency long before standard kidney-function tests raise a flag. Autonomic neuropathy, the nerve damage that diabetes inflicts on the involuntary nervous system, further blunts the erythropoietin response. Research in type 2 diabetes patients without advanced kidney failure found that the severity of cardiovascular autonomic neuropathy independently predicted both lower hemoglobin and a weaker erythropoietin response to anemia.4Journal of Diabetes and its Complications. Erythropoietin response to anemia and its association with autonomic neuropathy in type 2 diabetic patients without advanced renal failure So even when the kidneys are structurally intact enough to produce erythropoietin, the signaling chain that should ramp up production when hemoglobin drops can be broken.
Chronic Inflammation and Iron Trapping
Diabetes creates a state of chronic low-grade inflammation, and that inflammation triggers a cascade that starves the bone marrow of iron. The key player is hepcidin, a hormone produced in the liver. Inflammatory signals like interleukin-6 push hepcidin levels up, and elevated hepcidin blocks ferroportin, the protein that moves iron out of cells and into the bloodstream.5Indonesia Journal of Biomedical Science. The relationship between hepcidin and anemia in controlled and uncontrolled Type-2 Diabetes Mellitus (T2DM) patients at Sanglah Hospital, Bali, Indonesia The result is that you can have adequate iron stores locked inside cells while your blood plasma runs low on iron, leaving bone marrow unable to build enough hemoglobin. A study comparing anemic and non-anemic type 2 diabetes patients without significant kidney disease confirmed that the anemic group showed higher inflammatory markers and elevated hepcidin, even when erythropoietin levels were comparable between groups.6PubMed. Relationship between hepcidin and GDF15 in anemic patients with type 2 diabetes without overt renal impairment
Hyperglycemia and Red Blood Cell Damage
High blood sugar also attacks red blood cells directly. Chronic exposure to glucose modifies the proteins on the red blood cell membrane, forming compounds called advanced glycation end products that alter the membrane’s stability, fluidity, and ability to transport ions.7PubMed Central. Erythrocyte membrane in type 2 diabetes mellitus These changes accelerate aging of the red blood cell, leading to premature destruction or hemolysis and a shortened lifespan compared with red blood cells in people without diabetes.8PubMed Central. Red blood cells as biomarkers and mediators in complications of diabetes mellitus: A review When red blood cells die faster than bone marrow can replace them, hemoglobin drops.
On top of all this, diabetes can impair absorption of dietary iron through gastroparesis (delayed stomach emptying) and diabetic enteropathy, while hyperglycemia promotes urinary iron losses. Kidney disease with protein leakage in the urine further drains iron from the body.9PubMed Central. Implications of Iron Deficiency Anaemia on Glycemic Dynamics in Diabetes Mellitus: A Critical Risk Factor in Cardiovascular Disease
How Metformin Fits In
The most widely prescribed diabetes drug in the world, metformin, adds its own wrinkle. Metformin interferes with vitamin B12 absorption in the gut, and over time this can lead to deficiency.10PubMed Central. Association between metformin and vitamin B12 deficiency in patients with type 2 diabetes Data from the Diabetes Prevention Program Outcomes Study showed that combined low and borderline-low B12 was about twice as common in the metformin group as in the placebo group after five years of use, and each additional year on metformin raised the odds of B12 deficiency by about 13%.11PubMed Central. Long-term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study Severe B12 deficiency can cause megaloblastic anemia, in which the bone marrow produces abnormally large, dysfunctional red blood cells. If you have been on metformin for several years and feel progressively more fatigued, a B12 check is worth asking about. Periodic monitoring of B12 levels is a simple safeguard.
How Anemia Distorts HbA1c Readings
This is where the connection between anemia and diabetes gets especially practical. HbA1c, the blood test used to gauge average blood sugar over the previous two to three months, measures the percentage of hemoglobin that has been glycated, meaning sugar molecules have attached to it. The test assumes a normal red blood cell lifespan. When that assumption breaks down, so does the accuracy of the number on your lab report.
A systematic review found that iron deficiency, with or without outright anemia, tends to push HbA1c readings artificially higher, while non-iron-deficiency forms of anemia may push them lower.12PubMed. The effect of anaemia and abnormalities of erythrocyte indices on HbA1c analysis: a systematic review Research in non-diabetic patients confirmed this pattern: people with iron deficiency anemia had mean HbA1c readings of about 5.75%, compared with 5.32% in controls, and after iron treatment the HbA1c dropped to about 5.44% without any change in blood sugar.13PubMed Central. The effect of different types of anemia on HbA1c levels in non-diabetics That might not sound like a big gap, but in a person hovering around the diagnostic threshold for diabetes (6.5%), a false elevation from unrecognized iron deficiency could tip the reading over the line, leading to unnecessary treatment. At the other end, conditions that shorten red blood cell survival, including the hemolysis that hyperglycemia itself can cause, may make HbA1c look better than it really is, potentially masking poor blood sugar control.
The clinical headache intensifies in people on dialysis. In hemodialysis patients with diabetes, erythropoietin-stimulating treatments increase the proportion of young red blood cells in circulation. Because younger cells have spent less time in the bloodstream accumulating sugar, they carry less glycated hemoglobin, dragging the HbA1c reading down and potentially making glycemic control look better than it is.14Journal of the American Society of Nephrology. Glycated Albumin Is a Better Glycemic Indicator than Glycated Hemoglobin Values in Hemodialysis Patients with Diabetes
Alternatives to HbA1c When Anemia Is Present
When anemia makes HbA1c unreliable, clinicians can turn to glycated albumin. Because albumin is a blood protein with a half-life of about two to three weeks and is not affected by red blood cell turnover, glycated albumin gives a cleaner picture of short-term glycemic control. It has been recognized as a useful indicator specifically in settings where red blood cell abnormalities are present, including anemia, hemorrhage, and renal anemia.15Annals of Pediatric Endocrinology & Metabolism. Alternative biomarkers for assessing glycemic control in diabetes: fructosamine, glycated albumin, and 1,5-anhydroglucitol Fructosamine, another serum-protein-based marker, works on a similar principle. Neither test replaces HbA1c entirely, but using them alongside HbA1c can prevent you from being treated for a blood sugar problem you do not have, or from feeling falsely reassured about one you do.
Anemia and Diabetes Complications
The overlap is not just a diagnostic nuisance. Anemia appears to worsen diabetes-related complications. A study of type 2 diabetes patients found that anemia was a predictor of microvascular complications, the small-vessel damage behind diabetic retinopathy, neuropathy, and nephropathy.16PubMed Central. Anemia and Microvascular Complications in Patients With Type 2 Diabetes Mellitus Fewer red blood cells means less oxygen delivered to tissues that are already vulnerable. The retina, the peripheral nerves, and the kidneys are all sensitive to low oxygen, so anemia compounds the tissue damage that high blood sugar is already doing. And because anemia promotes fatigue and exercise intolerance, it can also make it harder to stay physically active, which is one of the most effective tools for managing blood sugar.
The Autoimmune Angle in Type 1 Diabetes
The mechanisms described above mostly apply to type 2 diabetes, but people with type 1 diabetes face an additional risk. Autoimmune conditions tend to cluster. Autoimmune gastritis, in which the immune system attacks the stomach lining, occurs at three to five times the usual rate in people with type 1 diabetes.17PubMed. Autoimmune gastritis in type 1 diabetes: a clinically oriented review Autoimmune gastritis destroys parietal cells, which produce the acid and intrinsic factor needed to absorb both iron and vitamin B12. Over time, this leads to iron deficiency anemia, B12 deficiency anemia, or both. Screening recommendations suggest that people with autoimmune gastritis antibodies should be regularly checked for the development of iron and B12 deficiency anemia, along with associated autoimmune thyroid disease.18PubMed. Diagnosis and classification of autoimmune gastritis If you have type 1 diabetes and unexplained fatigue, it is worth looking beyond blood sugar management at these overlapping autoimmune causes.
Pregnancy, Diabetes, and Anemia Together
Pregnancy raises the stakes because blood volume expands while iron demands surge. When gestational diabetes and anemia overlap, both mother and fetus face compounded risks. A study of pregnant women found that about 31% of those diagnosed with gestational diabetes were also anemic, with most cases falling in the mild-to-moderate range.19medRxiv. Influence of Anemia on Prevalence of Gestational Diabetes among Pregnant Women in Tripoli, Libya Social and environmental factors add layers of complexity. In a large retrospective study from North Palestine, pregnant women in refugee settings had a higher prevalence of anemia than those in rural or urban settings, while gestational diabetes rates varied in the opposite direction.20PLoS ONE. The epidemiology of gestational diabetes, gestation hypertension, and anemia in North Palestine from 2018 to 2020: A retrospective study Nutritional access, prenatal care availability, and baseline health all influence which condition dominates, but the co-occurrence is common enough that clinicians managing gestational diabetes should keep anemia on their radar and vice versa.
Managing Anemia in People With Diabetes
Treatment depends entirely on which mechanism is driving the anemia, and often more than one is involved simultaneously. A practical approach starts with identifying the type of anemia through a complete blood count and iron studies, then addressing each contributing factor.
- Iron deficiency: Oral iron supplements are the first-line treatment, though diabetic gastroparesis and enteropathy can impair absorption. Intravenous iron may be needed when oral supplements are poorly tolerated or ineffective. Correcting iron deficiency also removes a source of falsely elevated HbA1c, so post-treatment lab values may look different even without changes in blood sugar.
- B12 deficiency: Especially relevant for long-term metformin users. Oral or intramuscular B12 supplementation typically resolves the deficiency. Some clinicians recommend periodic B12 monitoring for anyone who has been on metformin for more than a few years.
- Erythropoietin deficiency: When kidney damage has impaired erythropoietin production, erythropoiesis-stimulating agents can raise hemoglobin. However, trials have shown that pushing hemoglobin to near-normal levels with high doses of these agents increases the risk of cardiovascular events like stroke and thrombosis. Current practice favors lower, individualized targets that balance symptom relief against safety.21PubMed. Erythropoiesis-stimulating agents in chronic kidney disease: what have we learned in 25 years?
- Inflammation-driven anemia: This is the trickiest to treat directly. Improving glycemic control helps reduce the chronic inflammatory state, which may lower hepcidin and free up iron stores. Anti-inflammatory interventions are an active area of research but do not yet have established protocols specific to diabetes-related anemia.
Quality of life matters too. Fatigue is the symptom most people with anemia notice first. In a randomized trial of diabetes patients with kidney disease, those treated with darbepoetin alfa (an erythropoiesis-stimulating agent) reported small but sustained improvements in fatigue and overall quality of life compared with placebo, lasting through nearly two years of follow-up.22PubMed Central. Darbepoetin alfa impact on health status in diabetes patients with kidney disease: a randomized trial The effect was modest in scale, which reinforces why targeting the underlying cause of anemia rather than relying solely on erythropoietin-boosting drugs is the better strategy when possible.
Newer Drugs With Unexpected Effects on Red Blood Cells
SGLT2 inhibitors, a class of diabetes drugs that lower blood sugar by blocking glucose reabsorption in the kidneys, have become a cornerstone of type 2 diabetes treatment, particularly for patients with heart failure or kidney disease. An intriguing side effect is that they consistently raise hematocrit, the proportion of blood volume made up of red blood cells. Initially, doctors assumed this was just dehydration from the drugs’ diuretic effect. Growing evidence now points to a different explanation: SGLT2 inhibitors appear to relieve kidney oxygen deprivation (hypoxia) and promote more efficient erythropoietin production, genuinely increasing the formation of new red blood cells.23PubMed. Increase in hematocrit with SGLT-2 inhibitors – Hemoconcentration from diuresis or increased erythropoiesis after amelioration of hypoxia? Research shows that SGLT2 inhibition promotes erythropoietin production and enhances iron mobilization.24PubMed Central. SGLT2 Inhibitors: Dual Effects on Erythropoiesis and Bone Metabolism This raises the interesting possibility that a drug originally designed for blood sugar could partly counteract the erythropoietin deficiency that diabetes causes. It is too early to prescribe SGLT2 inhibitors specifically to treat anemia, but for a person with diabetes who already benefits from the drug’s cardiovascular and renal effects, the bump in red blood cell production is a welcome bonus.
Another emerging class is the HIF-prolyl hydroxylase inhibitors, oral drugs in late-stage development that activate the body’s natural oxygen-sensing pathway to boost erythropoietin and correct anemia in chronic kidney disease.25PubMed Central. Hypoxia-inducible factor-prolyl hydroxylase inhibitors in the treatment of anemia of chronic kidney disease Because a large proportion of people with chronic kidney disease also have diabetes, these drugs may eventually reshape how anemia is managed in overlapping populations. Unlike injected erythropoiesis-stimulating agents, they are taken by mouth, which could simplify treatment for people already managing complex medication regimens.
When to Suspect the Two Conditions Are Interacting
If you have diabetes and notice worsening fatigue, dizziness, pale skin, or shortness of breath that does not line up with your blood sugar readings, anemia is worth investigating. The same goes for the opposite scenario: if you do not have a diabetes diagnosis but an HbA1c screening comes back surprisingly high while you feel fine, unrecognized iron deficiency could be inflating the number. A complete blood count, reticulocyte count, ferritin level, and B12 level can usually sort things out. For people already diagnosed with both conditions, asking your doctor about glycated albumin as a supplemental monitoring tool can help ensure that your treatment plan is based on accurate data rather than on an HbA1c number that anemia has skewed in one direction or the other.