SGLT2 Medicines Like Jardiance and Farxiga May Slightly Raise Hemoglobin on Upcoming Blood Tests

People who take SGLT2 inhibitors for type 2 diabetes, heart failure, or chronic kidney disease may notice slightly higher hemoglobin and hematocrit results on routine blood tests, according to a review published in JAMA.

The analysis combined 85 randomized, double-masked clinical trials involving 70,543 adults. Compared with placebo or other diabetes medications, SGLT2 inhibitors increased hemoglobin by about 0.6 grams per deciliter and hematocrit by roughly 2.4 percentage points over a median follow-up of 24 weeks. The researchers said, "The increases were small and clinical significance remains uncertain."

For patients and caregivers who review lab results in an online portal, the change may prompt questions. A hemoglobin value marked high can seem concerning, while a rise in someone with anemia may be welcome. The study does not alter current treatment advice, but it may help patients understand what to expect before a follow-up visit.

What the 85-Trial Review Showed

The trials included drugs such as empagliflozin (Jardiance), dapagliflozin (Farxiga), canagliflozin (Invokana), ertugliflozin (Steglatro), sotagliflozin (Inpefa) and bexagliflozin (Brenzavvy). Participants were about 62 years old on average, and around 36% were women. The studies came from North America, Europe and Asia, and 38 trials had at least one U.S. site.

The hemoglobin rise was similar across people with diabetes, heart failure and kidney disease, although results varied widely from one trial to another. In further analyses, the effect was larger at higher doses and with longer treatment, reaching about 0.71 g/dL at 48 weeks. The researchers said part of the increase may reflect fluid loss, since these drugs increase urination. Erythropoietin levels, which help stimulate red blood cell production, also rose slightly, and red blood cell counts went up as well.

Iron-related markers changed too. Ferritin, which reflects stored iron, and transferrin saturation both fell, while blood iron levels did not change significantly. That pattern is consistent with the body using iron to make new red blood cells, though the study was not designed to prove that mechanism.

This systematic review and meta-analysis of randomized trials provides strong evidence for the laboratory changes themselves. It did not examine heart attacks, strokes, clots or other clinical outcomes. Only about 7% of participants had iron data, and red blood cell mass was never measured directly.

The research was led by investigators at University Medical Center Groningen in the Netherlands, with collaborators including Brigham and Women's Hospital in Boston. The team registered its plan in advance and assessed each trial for bias. None of the 85 trials was judged to be at high risk of bias, and removing any single study did not alter the main result.

Why the Lab Change Matters

For people with anemia related to kidney disease or heart failure, a modest increase may be helpful. In an accompanying editorial, Dr. Kai-Uwe Eckardt of Charité-Universitätsmedizin Berlin and Dr. Mark J. Koury of Vanderbilt University Medical Center in Nashville wrote that the rise may support anemia management. For comparison, the study noted that injectable anemia drugs known as erythropoiesis-stimulating agents can raise hematocrit by about 5% to 11%.

The editorial also urged caution. SGLT2 medicines can increase the risk of erythrocytosis, a condition in which too many red blood cells are present in the blood, and the authors highlighted particular concern for people with heart failure. If that happens, they said doctors should balance the benefits of the drugs against the risk of clots. They wrote that "dose reduction or discontinuation with resumption at a lower dose may be options."

Real-world evidence suggests the issue is usually limited. In a single-center registry of 1,244 heart failure patients in Croatia, about 8% of those with normal baseline levels developed erythrocytosis by six months. It was often temporary and was not associated with worse outcomes, though the researchers noted that the small sample limits firm conclusions.

What to Do Before Your Next Appointment

Patients should not stop or adjust an SGLT2 medicine on their own. These drugs reduce the risk of heart failure hospitalization and kidney decline for many people, and stopping them suddenly could remove that protection. Questions about lab values are best addressed by the clinician who prescribed the medication.

Before a visit, it helps to bring an up-to-date medication list and recent test results. Patients can ask whether a small hemoglobin rise is expected, how their numbers have changed over time, and whether any follow-up is needed. A single result matters less than the overall trend.

Some symptoms require urgent care regardless of lab numbers. These include swelling or pain in one leg, sudden shortness of breath, chest pain, or sudden weakness and trouble speaking. These can be signs of a blood clot or stroke and should not wait for a routine appointment.

Cost and insurance coverage also affect access. Medicare beneficiaries can use the open enrollment period to check whether their SGLT2 medicine will still be covered. The researchers said more studies are needed before doctors know whether the blood-count rise is mainly beneficial or sometimes harmful.

Questions and Answers

What did the JAMA review find?

Across 85 trials, SGLT2 inhibitors raised hemoglobin by about 0.6 g/dL and hematocrit by about 2.4 percentage points compared with control treatments.

Which medicines are SGLT2 inhibitors?

They include Jardiance, Farxiga, Invokana, Steglatro, Inpefa and Brenzavvy. Depending on the medication, they are used for type 2 diabetes, heart failure or chronic kidney disease.

Is a higher hemoglobin level dangerous?

Usually the change is small. In some people, it can lead to erythrocytosis, which may raise clot risk, so doctors weigh the benefits and risks.

Should I stop taking my SGLT2 medicine?

No. Do not stop or change a prescribed medicine without speaking with the clinician who prescribed it.

Could this help people with anemia?

Possibly. The editorial writers said the modest rise may help with anemia management, though more research is needed.

When should I seek urgent care?

Seek immediate care for one-sided leg swelling or pain, sudden shortness of breath, chest pain, or sudden weakness or trouble speaking.