Fluoroquinolones (FQs) have been reported to cause dysglycemia in both diabetic and non-diabetic patients. However, diabetic patients are usually on polypharmacy, so we cannot attribute the dysglycemia specifically to FQs. To answer the question as to whether Moxifloxacin and Gemifloxacin influence blood glucose levels and serum insulin levels or otherwise, rabbits were used as experimental animals in an in vivo model followed by a phase I randomized clinical trial in euglycemic healthy volunteers. The effects on the serum insulin and blood glucose levels in the Moxifloxacin and Gemifloxacin treated groups were, respectively, determined on the fifth day in both the in-vivo rabbits model and in the test subjects of the phase I clinical trial. The effects of these drugs were also checked on the histomorphology of the pancreas in the rabbits. The findings of our study suggest that Moxifloxacin and Gemifloxacin significantly (p < 0.05) reduced the blood glucose levels via a subsequent significant shift in the serum insulin levels both in the in vivo animal model and in the test subjects of the phase I clinical trial. No prominent effects on the beta cells histomorphology were noted in this study. Moxifloxacin showed a more significant effect than Gemifloxacin. The insulinotropic effect was comparable to the effect of Glibenclamide. It is concluded that Moxifloxacin and Gemifloxacin have a significant blood glucose lowering effect mediated through insulinotropic action. (Clinical Trials.gov identifier: NCT04692623).