Objetives <p>We aimed to examine the effects of newly started SGLT2 inhibitors on thiamine levels.</p> Background <p>High glucose in the renal tubular epithelium causes increased renal clearance of thiamine. Therefore, we hypothesized that glucosuria induced by SGLT2 inhibitors may result in thiamine deficiency.</p> Methods <p>The SGLT2 inhibitors group included patients who were added to their treatment with an SGLT2 inhibitor and who did not have glucosuria. The control group comprised patients who were taking medications other than SGLT2 inhibitors. Patients in both groups were followed for three months.</p> Results <p>The study was completed by 27 patients in each group, with a mean age of 53.2 ± 9.6&#xa0;years. At baseline, the SGLT2 inhibitors group had worse glycemic control compared to the control group (p &lt; 0.001), but no difference for thiamine. In the SGLT2 inhibitors group, but not in the control group, there were significant decreases in glucose, HbA1c, and creatinine values at the end of the 3-month follow-up, accompanied by a significant increase in thiamine levels.</p> Conclusion <p>Glucosuria induced by SGLT2 inhibitors did not lead to a decrease in whole-blood thiamine levels. Whole-blood thiamine levels increased with improved glycemic control. SGLT2 inhibitors demonstrated favourable effects on both glycemic control and creatinine levels.</p>