A randomized, open-label, parallel study was conducted to assess the efficacy and safety of premixed insulin aspart 30 (biphasic insulin aspart [BIAsp] 30) in managing gestational diabetes mellitus (GDM). A total of 323 women with GDM registered at a single center in India were randomly assigned to receive 6 U of either BIAsp 30 (Group A) or premixed human insulin (biphasic human insulin [BHI] 30; Group B) in a 1:1 ratio. Subjects performed home glucose monitoring and visited their care provider twice a month. The primary outcome was the degree of neonatal macrosomia (neonatal birth weight >90th percentile). Groups A and B were demographically comparable at study entry. Before labor onset, Groups A and B achieved similar degrees of fasting plasma glucose and postprandial plasma glucose control (92.97 ± 14.44 vs. 95.43 ± 18.96 and 127.59 ± 28.99 vs. 126.98 ± 29.89, respectively; both p = NS). Neonatal macrosomia frequency was 6.3% in Group A and 6.9% in Group B; however, this difference was not statistically significant. By last visit, the required insulin dose was significantly lower for Group A than Group B (19.83 ± 15.75 IU vs. 26.34 ± 23.15 IU, respectively; p = 0.006). BIAsp 30 was noninferior to BHI 30, producing comparable fetal outcomes when administered during pregnancy. Based on final doses, BIAsp 30 may offer greater treat-to-target potential for pregnant women.