Maternal hyperglycemia during pregnancy poses significant health risks to both mother and fetus. Although gestational diabetes mellitus (GDM) is mainly characterized by insulin resistance, severe hyperglycemia may also result from impaired pancreatic function. This study evaluates the therapeutic potential of pandan (Pandanus amaryllifolius) root and teak (Tectona grandis) leaf extracts in managing streptozotocin (STZ)-induced maternal hyperglycemia in pregnant rats, compared to metformin. Methods: Pregnant rats were administered STZ (60 mg/kg) on gestation day 5. Treatments with metformin (300 mg/kg), pandan extract (low, medium, high doses), and teak extract (low, medium, high doses) were given from gestation day 7 to 21. The key parameters included the maternal blood glucose, insulin levels, pancreatic morphology, fetal and placental outcomes, and gas chromatography/mass spectrometry (GC/MS) phytochemical profiling. GC/MS analysis identified 2,3-butanediol and propanoic acid derivatives as major compounds in pandan, while teak contained catavic acid and methyl copalate. The high-dose pandan extract significantly reduced the maternal blood glucose (p < 0.05), improved the insulin levels and pancreatic mass index, and increased the number of live fetuses, with effects comparable to metformin. The teak extract showed milder improvements. The pandan extract demonstrated dose-dependent antidiabetic potential in this STZ-induced model. Future studies should evaluate these effects in insulin-resistance-based GDM models.