Effects of SGLT2 inhibitors on eGFR in type 2 diabetic patients-the role of antidiabetic and antihypertensive medications

Recent randomized trials demonstrating the beneficial effects of sodium-glucose cotransporter 2 inhibitors (SGLT2is) in type 2 diabetes suggest that early reductions in eGFR upon initiation of SGLT2i therapy are associated with improved renal outcomes. Multiple concomitant medications, including antidiabetic and antihypertensive agents, are commonly used, however, which may modify the renal hemodynamic action of SGLT2is. Here we found that background treatment with metformin diminished the SGLT2i-induced reductions in eGFR after 3 months of SGLT2i therapy in patients with type 2 diabetes and hypertension (-2.29 ± 0.90 vs -5.85 ± 1.27 mL/min/1.73 m2 for metformin users (n = 126) and nonusers (n = 97), respectively). Other antidiabetic agents (DPP4 inhibitors, sulfonylureas and insulin) had no effect on the eGFR response to SGLT2is. Antihypertensive drugs, including calcium channel blockers (CCBs) and β blockers, did not affect the SGLT2i-induced changes in eGFR, whereas renin-angiotensin system inhibitors (RASis) tended to enhance this response (p = 0.059). Next, we evaluated the interaction between metformin and RASis in the eGFR responses to SGLT2is. Under no background treatment with RASis, metformin abrogated the eGFR response to SGLT2is, but this response was preserved when RASis had been given along with metformin (decreases of 0.75 ± 1.28 vs. 4.60 ± 1.15 mL/min/1.73 m2 in eGFR, p = 0.028). No interaction between metformin and insulin or between metformin and DPP4 inhibitors was observed. In conclusion, metformin blunts the SGLT2i-induced decrease in eGFR, but coadministration of RASis ameliorates this response. Furthermore, the inability of CCBs to modify the SGLT2i-induced reduction in eGFR suggests that the SGLT2i-induced renal microvascular action is mediated predominantly by postglomerular vasodilation rather than preglomerular vasoconstriction.