Diabetes In Control. A free weekly diabetes newsletter for Medical Professionals. News and information for Medical Professionals.
How SGLT2 Inhibitors Affect Hemoglobin and Heart Health
Could a small change in a routine blood test help explain why certain diabetes medications protect the heart and kidneys? A new JAMA meta-analysis explores how SGLT2 inhibitors affect hemoglobin levels and red blood cell production. Researchers found consistent increases in hemoglobin and hematocrit across 85 randomized clinical trials involving more than 70,000 participants. However, whether these changes contribute directly to better cardiovascular and kidney outcomes remains uncertain.
Table of Contents
- What the JAMA Meta-Analysis Found
- Why SGLT2 Inhibitors May Increase Hemoglobin Levels
- Could Higher Hemoglobin Explain Cardiorenal Protection?
- Clinical Implications and Future Research
- Conclusion
- Frequently Asked Questions
What the JAMA Meta-Analysis Found
Published in JAMA on October 24, 2026, the systematic review and meta-analysis evaluated 85 randomized, double-masked clinical trials involving 70,543 participants. These studies included people with diabetes, cardiovascular disease, heart failure, or chronic kidney disease.
Researchers examined changes in hemoglobin, hematocrit, erythropoietin, and markers of iron metabolism. The median trial duration was 24 weeks.
Compared with control groups, SGLT2 inhibitors produced an average hemoglobin increase of 0.60 g/dL. Hematocrit also increased by 2.36 percentage points. Both findings were statistically significant.
The analysis included commonly prescribed medications such as empagliflozin (Jardiance), dapagliflozin (Farxiga), canagliflozin (Invokana), and ertugliflozin (Steglatro).
Importantly, these effects appeared across different disease categories. Therefore, they may reflect biological actions that extend beyond blood glucose lowering.
The investigators also found increased red blood cell concentrations and higher erythropoietin levels. Meanwhile, ferritin and transferrin saturation declined, suggesting changes in iron handling.
Although the overall findings were consistent in direction, the size of the effects varied considerably between studies. Furthermore, the evidence was rated as moderate certainty for hemoglobin and hematocrit.
The researchers concluded that the increases were small and that their clinical significance remained uncertain.
Why SGLT2 Inhibitors May Increase Hemoglobin Levels
SGLT2 inhibitors lower blood glucose by helping the kidneys remove excess glucose through urine. However, their effects reach beyond glucose management.
One possible explanation for rising hematocrit is a reduction in plasma volume. Because these medications promote sodium and water loss, the blood may initially become more concentrated.
Yet fluid changes may not explain the entire response.
The meta-analysis found that erythropoietin levels increased by an average of 2.11 mIU/mL compared with controls. Erythropoietin is a hormone that signals the bone marrow to produce red blood cells.
Additionally, red blood cell concentrations increased, supporting the possibility of greater red blood cell production.
Researchers have proposed that changes in kidney function and oxygen signaling may influence this process. However, the analysis did not directly establish the cellular pathways involved.
What Changes in Iron Metabolism Mean
Iron is essential for making hemoglobin, the protein that carries oxygen throughout the body.
Interestingly, the analysis found decreases in ferritin and transferrin saturation among patients receiving SGLT2 inhibitors.
Ferritin reflects stored iron, while transferrin saturation indicates how much circulating iron is available for use.
These changes could be consistent with increased iron utilization during red blood cell production. However, lower iron markers do not automatically prove that more iron is being used to create red blood cells.
The analysis also found no statistically significant change in serum iron or hepcidin, a hormone involved in iron regulation.
Consequently, the findings suggest a complex relationship between kidney signaling, red blood cell production, and iron metabolism that deserves further study.
Could Higher Hemoglobin Explain Cardiorenal Protection?
SGLT2 inhibitors have demonstrated cardiovascular and kidney benefits in major clinical trials. These benefits include reduced hospitalization for heart failure and slower progression of certain forms of chronic kidney disease.
For example, previous research discussed by Diabetes in Control on empagliflozin and heart failure highlights how these medications may benefit patients regardless of diabetes status.
The latest findings raise an important question: Could increased hemoglobin contribute to these protective effects?
Hemoglobin delivers oxygen to tissues, including the heart and kidneys. In theory, improved oxygen-carrying capacity might support tissue function in certain patients.
Furthermore, changes in erythropoietin and red blood cell production may reflect broader changes in kidney physiology.
However, an association between higher hemoglobin and improved outcomes does not establish causation.
The JAMA analysis specifically examined blood measurements rather than cardiovascular events, kidney failure, or survival. Therefore, it cannot determine whether the observed hemoglobin increases caused any clinical benefit.
Other proposed mechanisms of SGLT2 inhibitor protection include changes in kidney filtration pressure, fluid balance, blood pressure, and cardiac workload.
These pathways may operate together rather than independently.
As a result, hemoglobin changes should currently be viewed as an interesting biological signal, not a proven explanation for cardiorenal protection.
Clinical Implications and Future Research
For clinicians treating type 2 diabetes, heart failure, or chronic kidney disease, the findings provide useful context for interpreting routine blood tests.
A slight increase in hemoglobin or hematocrit may be an expected response to SGLT2 inhibitor treatment. However, individual results still require clinical assessment.
An unusually high hematocrit, persistent anemia, or abnormal iron studies should not automatically be attributed to medication effects.
Instead, clinicians should consider hydration status, kidney function, underlying blood disorders, and other possible causes.
The results also raise questions about patients who already have anemia or iron deficiency.
Although erythropoietin increased in the pooled analysis, the findings do not establish SGLT2 inhibitors as treatments for anemia. Moreover, only a relatively small subset of participants contributed iron biomarker data.
Additional studies should investigate whether blood changes predict cardiovascular or kidney outcomes at the individual patient level. Researchers also need to separate true increases in red blood cell mass from changes caused by plasma volume.
For now, established clinical indications and patient-specific factors should guide treatment decisions rather than attempts to raise hemoglobin.
Clinicians seeking additional context can review Diabetes in Control's coverage of SGLT2 inhibitors and kidney outcomes.
Conclusion
The new JAMA meta-analysis adds to growing evidence that SGLT2 inhibitors can modestly raise hemoglobin and hematocrit levels. It also identifies changes in erythropoietin, red blood cell concentration, and iron metabolism that may help researchers understand these effects.
Nevertheless, the findings do not prove that higher hemoglobin causes better cardiovascular or kidney outcomes.
For clinicians, the key takeaway is to recognize these blood changes while continuing to base treatment on established benefits, appropriate monitoring, and individual patient needs.
Frequently Asked Questions
1. Can SGLT2 inhibitors raise hemoglobin levels?
Yes. The JAMA meta-analysis found an average increase of approximately 0.60 g/dL compared with control groups. However, the magnitude varied across studies, and individual responses may differ.
2. Why do SGLT2 inhibitors increase hematocrit?
Potential explanations include reduced plasma volume and increased red blood cell production. Higher erythropoietin levels support the latter possibility, although the exact contribution of each mechanism remains uncertain.
3. Can higher hemoglobin explain the heart and kidney benefits of SGLT2 inhibitors?
Possibly, but this relationship has not been proven. The meta-analysis measured blood changes rather than testing whether higher hemoglobin improves cardiovascular or kidney outcomes.
4. Can SGLT2 inhibitors treat anemia in patients with chronic kidney disease?
SGLT2 inhibitors may raise hemoglobin in some patients, but this analysis does not establish them as anemia treatments. Patients with anemia still need evaluation and treatment based on its underlying cause.
5. Should clinicians routinely monitor hemoglobin during SGLT2 inhibitor therapy?
Hemoglobin and hematocrit may be assessed as part of routine care, particularly when patients have anemia, kidney disease, or unusual blood test results. However, this meta-analysis does not establish a new requirement for routine hemoglobin monitoring solely because a patient takes an SGLT2 inhibitor.
Reference
Yang Y, Yang C, Wang Y, et al. Sodium-Glucose Cotransporter 2 Inhibitor Use and Levels of Hemoglobin, Markers of Iron Metabolism, and Erythropoiesis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. JAMA. Published online October 24, 2026. doi:10.1001/jama.2026.19921.
Disclaimer
This content is not medical advice. For any health issues, always consult a healthcare professional. In an emergency, call 911 or your local emergency services.