Aim: The study evaluated the effect of prophylactic antenatal corticosteroids (ACSs) on maternal blood glucose (MBG) changes and insulin requirement in gestational diabetes mellitus (GDM). Materials and methods: Patients with GDM received a conventional ACS regimen. Pre-meal glucose levels determined initiation of insulin or dose titration if already on insulin. All were monitored for 72 hours after the first dose of ACS. From day 3, fasting blood glucose, one hour post-meal glucose levels were assessed. Glycemic monitoring was continued for five days in those who had hyperglycemia during the first 72 hours after ACS. Results: Of the 52 patients, 12 required insulin for the first time and 14 were already on it before ACS, remaining were managed with medical nutritional therapy (MNT). Maternal blood glucose declined from day 3 onwards, euglycemic status was reached on day 4 and sustained on day 5. There was no significant change in the mean MBG during the first two days following ACS, but a gradual decline from day 3 was noticeable. The mean MBG change was independent of duration. There was a significant difference between the average insulin requirements. There was no fetal loss. Conclusion: Antenatal corticosteroid-induced hyperglycemia increases the requirement of insulin, or add on oral hypoglycemic agents. Well-controlled glycemic status is achievable with MNT alone or in combination with pharmacotherapy under continued monitoring. Clinical significance: Continuous monitoring, MNT to meet the increased nutritional needs, not increase MBG levels at the same time, and add on pharmacotherapy should be included in the treatment strategy.