SGLT2 Inhibitors Tied To Uptick In Hemoglobin And Hematocrit

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A meta-analysis of 85 randomized trials involving 70,543 people found that SGLT2 inhibitor treatment was associated with higher hemoglobin and hematocrit than control treatment over a median 24 weeks. The findings also point to changes in erythropoietin and iron-related measures, but the trials did not establish the mechanism or whether the changes improve anemia outcomes.

A systematic review and meta-analysis of 85 randomized trials found that SGLT2 inhibitors were associated with modest increases in hemoglobin and hematocrit compared with control treatment across more than 70,000 people with conditions including chronic kidney disease, heart failure and type 2 diabetes. The results, presented at the American Society of Nephrology Kidney Week meeting and published in JAMA, may inform research into anemia management, but do not establish that the changes improve anemia or explain the drugs’ cardiorenal benefits.

Across 70,543 participants, hemoglobin rose by an average of 0.55 g/dL in SGLT2 inhibitor groups and fell by 0.08 g/dL in control groups over a median of 24 weeks. The reported between-group difference was 0.60 g/dL (95% CI 0.55-0.66; P<0.001). Hematocrit increased by 2.17% with treatment and declined by 0.13% in control groups, a between-group difference of 2.36 percentage points (95% CI 2.19-2.52; P<0.001).

Four of six secondary measures also differed significantly between groups. Erythropoietin increased by 2.35 mIU/mL compared with 0.04 mIU/mL in controls, while red blood cell concentration rose by 0.23 × 10¹²/L compared with 0.02 × 10¹²/L. Ferritin fell by 19.78 ng/mL versus 3.08 ng/mL, and transferrin saturation fell by 2.20% versus 0.10%. Changes in hepcidin and serum iron did not reach statistical significance.

The analysis included double-blind trials of SGLT2 inhibitors used alone or alongside other treatments. Participants had a mean age of 62.4 years; 35.9% were female. Mean baseline hemoglobin was 13.6 g/dL and hematocrit was 41.5%. The trials covered several drugs in the class, with most evaluating empagliflozin or dapagliflozin.

Possible Relevance to Anemia Care

The findings add evidence that SGLT2 inhibitors affect measures related to red blood cell production and iron metabolism, not just fluid balance. That may matter for patients with chronic kidney disease or heart failure, who can also experience anemia. The authors said the modest hemoglobin rise could potentially contribute to anemia management, but this pooled analysis does not show that patients’ anemia symptoms or outcomes improved because of the change.

The results also should not be read as a reason to start or change medication for anemia. SGLT2 inhibitors are studied and used for several chronic conditions, and the review examined blood measurements across trials rather than testing a specific anemia-treatment strategy. The authors said future research needs to determine whether the hematologic changes directly contribute to cardiorenal benefits or affect the need for conventional anemia treatments.

What the Trial Pool Examined

Earlier research had already observed increases in hemoglobin and hematocrit during SGLT2 inhibitor treatment. This review brought together 85 randomized clinical trials involving people with chronic kidney disease, heart failure, type 2 diabetes, cardiovascular disease, or overlapping conditions. Its broad trial base allowed researchers to compare changes in blood measures between treatment and control groups across varied patient populations.

Post hoc analyses suggested the hemoglobin difference varied with dose and follow-up duration: it reached 0.65 g/dL at 1.5 times the standard clinical dose and 0.71 g/dL at 48 weeks. These are analyses conducted after the main comparisons and do not, on their own, establish how a particular dose or treatment duration should be used.

“This is the largest and most comprehensive analysis to date of the effects of SGLT2 inhibitors on hematologic and iron-related parameters.”

— Michele F. Eisenga, MD, PhD, of University Medical Center Groningen, speaking to MedPage Today

Mechanism and Patient Risks

The analysis cannot establish why hemoglobin and hematocrit rose or whether those changes improve health outcomes. Eisenga and colleagues interpreted the pattern of higher erythropoietin alongside lower ferritin and transferrin saturation as consistent with changes in red blood cell production and iron metabolism. However, editorial authors noted that trial data on red blood cell indices were limited, and measurements of red blood cell mass, plasma volume and red blood cell lifespan were not reported. Those measurements would help test whether red blood cell mass actually increased.

The authors also cautioned that people with already elevated baseline hemoglobin or hematocrit could potentially face a greater risk of thromboembolic events if levels rise further. The supplied findings do not quantify that risk or establish which patients might be affected. Whether the observed blood changes drive cardiorenal benefits, contribute meaningfully to anemia management, or alter use of conventional anemia treatments remains unresolved.

Questions for Future Trials

The researchers said future trials should test whether changes in hemoglobin and related measures directly contribute to the kidney and heart benefits associated with SGLT2 inhibitors. Studies that include direct measurements of red blood cell mass and related variables could clarify the mechanism identified as a limitation in the available trial data.

Further research will also need to determine whether the modest rise has a measurable role in anemia management and whether it affects reliance on conventional treatments. Until those questions are answered, the results describe average changes across trial groups; they do not establish an individual patient’s likely response or provide evidence to change treatment on their own.

Key Questions

How much did hemoglobin change in the analysis?

Hemoglobin rose by an average of 0.55 g/dL in SGLT2 inhibitor groups and fell by 0.08 g/dL in control groups over a median of 24 weeks. The reported between-group difference was 0.60 g/dL.

Did hematocrit also increase?

Yes. Hematocrit rose by an average of 2.17% in treatment groups and declined by 0.13% in control groups, a between-group difference of 2.36 percentage points.

Does the review prove SGLT2 inhibitors treat anemia?

No. It found differences in blood measurements across randomized trials, but did not establish that the changes improve anemia symptoms or outcomes. The authors said further research is needed.

What remains uncertain about the cause of the increases?

The results suggest the changes may involve erythropoietin and iron metabolism, but the trials did not report direct measurements of red blood cell mass, plasma volume or red blood cell lifespan. The mechanism is not confirmed.

Did the authors identify a possible safety concern?

They cautioned that further increases in people with already elevated hemoglobin or hematocrit could potentially raise thromboembolic risk. The report did not quantify that risk or identify which patients would be affected.

Source: rss