This study aimed to assess the safety of SGLT2 inhibitors in type 2 diabetes, chronic kidney disease, and chronic heart failure considering the number needed to treat (NNT).Methods: Data were obtained from 10 morbidity-mortality trials and were pooled to calculate the NNTs. The number needed to treat to benefit (NNTB) is used to express beneficial outcomes, whereas the number needed to treat to be harmed (NNTH) is used for harmful outcomes. The eight safety outcomes of interest were fracture, diabetic ketoacidosis, amputation, urinary tract infection, genital infection, acute kidney injury, severe hypoglycemia, and volume depletion.A total of 10 trials involving 76319 patients were included in this meta-analysis. The mean follow-up was 2.35 years. SGLT2 inhibitors play a positive role in acute kidney injury and severe hypoglycemia, with the corresponding mean NNTBs being 157 and 561, respectively. SGLT2 inhibitors significantly increased the risk of diabetic ketoacidosis, genital infection, and volume depletion, with the corresponding mean NNTHs being 1014, 41, and 139. It was found that the safety of SGLT2 inhibitors was the same in three diseases and five SGLT2 inhibitors.SGLT2 inhibitors have a positive impact on acute kidney injury and severe hypoglycemia, but they increase the incidence of diabetic ketoacidosis, genital infection, and volume depletion.