Introduction: The incidence of Gestational Diabetes Mellitus (GDM) is rising globally with India no exception. The overall prevalence of GDM in our country is 16.55%. Insulin is the gold standard for the treatment of diabetes. Metformin, an Oral Hypoglycaemic Agent (OHA) is promisingly used in place of or along with Insulin. Myoinositol an insulin sensitiser may have some role in the treatment of GDM. Aim: To assess whether myoinositol in addition to metformin provides any better glycaemic control in GDM patients than those receiving metformin only. Materials and Methods: An open-label randomised clinical trial was conducted in the Department of Obstetrics and Gynaecology of Medical College and Hospital, Kolkata, West Bengal, India, in which mothers with a singleton pregnancy with 2-hour Postprandial Blood Sugar (PPBS) ≥140 mg/dL after 75 gm oral glucose {Diabetes in Pregnancy Study Group of India (DIPSI) criteria} were included and those with pregestational diabetes, on any form of anti-diabetic treatment and with other co-morbidities like renal pathology, hypertension were excluded. A total of 150 patients with GDM were given Medical Nutrition Therapy (MNT) and after two weeks, 66 patients were selected and randomly allocated into two groups. Group 1 was given Myoinositol along with metformin (n=33) and group 2 was given metformin only (n=33). Dropouts were three in each group. So, a net of 30 patients from each group was taken for the final analysis. A p-value ≤0.05 was considered statistically significant. Results: The mean change in fasting glucose levels in group 1 was 19.30±9.713 mg/dL whereas in group 2 was 20.76±13.70 mg/dL. (p=0.6343). The mean change in postprandial blood glucose was 59.4667±16.8026 mg/dL in group 1 and 54.7667±18.8674 mg/dL in group 2. Both these results were statistically not significant. Two (6.7%) patients required insulin in group 1 and in group 2, 5 (16.7%) patients had insulin added. Association was not statistically significant (p=0.2276). Conclusion: Myoinositol supplementation with metformin achieves good glycaemic control through its insulin-sensitising action and reduces the complications of GDM to a certain extent but it does not provide any extra benefits over metformin alone.