Aims: Gestational diabetes mellitus (GDM), one of the most prevalent and notorious medical disorders complicating pregnancy, is known to be associated with chronic low-grade inflammation which triggers endothelial injury and platelet activation. Mean platelet volume (MPV) has been hypothesized to be higher in GDM which may aid in early diagnosis and appropriate management of this complication. The aim of our study was to determine whether an association exists between MPV and the diagnosis of GDM and to compare various platelet indices in pregnant women with and without GDM. Materials and methods: All participants underwent a 50 gm glucose challenge test. If the 1 hour blood glucose level was = >140 mg/dL, these women were further subjected to a 100 gm oral glucose tolerance test which was interpreted according to the Carpenter and Coustan criteria. Women diagnosed with GDM were considered as cases (N = 73) and those with a negative screening test as controls (N = 73). Other platelet parameters were measured and then compared between the two groups. Results: The difference in MPV (p = < 0.001) and platelet count (p = 0.01) between cases and controls was found to be statistically significant. Pregnant women with GDM had a significantly higher MPV and lower platelet count. In addition, a statistically significant positive correlation was found between the GCT value and the MPV and an inverse correlation was noted between the GCT value and the platelet count. Conclusion: A significant difference between the values of MPV and platelet count in patients with GDM as compared with healthy pregnant women, at the time of diagnosis, aids in supporting evidence that mean platelet volume may be used as a marker for GDM. A positive correlation between MPV and value of GCT and an inverse relationship between the platelet count and GCT values further suggests that these markers may also be used to study disease severity and worse blood sugar derangements may be expected when they are deranged. Clinical significance: Our study has proven that the value of MPV in patients with a fresh diagnosis of GDM lies in the high normal range, when compared with healthy matched controls. This and the knowledge of differences in other platelet parameters would help not only in prediction and early diagnosis of pregnant women with GDM but also provide a tool to better predict complications and improve maternal and neonatal outcomes.