In several studies, Sodium-glucose co-transporter-2 inhibitors (SGLT2i) have been reported to increase hemoglobin (Hb) levels. In a study in which Hb levels were compared between patients who received SGLT2i and dipeptidyl peptidase-4 inhibitors, some patients exhibited increased Hb levels (>1.0 g/dl), whereas some exhibited unchanged Hb levels. Notably, several factors may influence the Hb-increasing effect of SGLT2i. This study aimed to analyze the factors influencing the Hb-increasing effect of SGLT2i. Type 2 diabetes patients were divided into three groups: SGLT2i (SGLT2i only group, n=36), those receiving a combination of SGLT2i and angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARBs) (SGLT2i+ACEi/ARBs group, n=32), and those not receiving these drugs (control group, n=49). We retrospectively analyzed Hb changes in these groups. Kaplan-Meier curves compared Hb changes from SGLT2i initiation to day 63, with an Hb increase defined as ≥0.5 g/dl. In addition, sex, age, ACEi/ARBs, estimated glomerular filtration rate, and hematocrit levels were analyzed using Cox proportional hazards as factors influencing Hb-increasing events. Hb-increasing event rates were 61%, 41%, and 20% in the SGLT2i only, SGLT2i+ACEi/ARBs, and control groups, respectively. The Kaplan-Meier curves showed significantly higher Hb-increasing event rates in the SGLT2i only group than in the control and SGLT2i+ACEi/ARBs groups. In the Cox proportional hazards model, ACEi/ARBs use was associated with a 39% reduction in the incidence of Hb-increasing events. SGLT2i exhibit a Hb-increasing effect, which may be reduced by ACEi/ARBs.