Background: Type 2 Diabetes Mellitus is a chronic metabolic condition marked by insulin resistance and β-cell impairment, resulting in hyperglycaemia and related consequences. While pharmaceutical interventions are standard, the increasing interest in nutraceuticals has driven research into herbal formulations. Methods: This was a prospective, randomized, double-blind, placebo-controlled, two-arm, parallel-group, multi-center study conducted across two clinical sites in Pune, India. Forty adult patients (aged 18–70 years) with established T2DM on stable conventional therapy were grouped randomly in a 1:1 ratio to receive either Rasayanam Gluco-Care (30 ml twice daily) or a placebo juice for 30 days. An alteration in glycosylated haemoglobin (HbA1c) between baseline to Day 30 was the primary endpoint. Secondary endpoints encompassed alterations in Quality of Life (QoL) assessed with the QOLID22 questionnaire, safety assessments through adverse event (AE) monitoring, and changes in haematological parameters. Results: All 40 randomized subjects completed the study, with no protocol deviations affecting analysis. Baseline demographics were balanced between groups with no statistically significant differences in age, gender, BMI, or clinical history. The Rasayanam group demonstrated significantly reduced HbA1c levels compared to the placebo group. The mean change in HbA1c from baseline to Day 30 was -1.04% in the Rasayanam group, compared to +0.08% in the placebo group (p < 0.001). The least squares mean difference in HbA1c between groups was -1.18% (95% CI: -1.44 to -0.92), demonstrating strong statistical and clinical relevance. No significant adverse events or treatment-emergent adverse events (TEAEs) were documented. The findings of this study can therefore act as a catalyst for incorporating proven Ayurvedic formulations into conventional diabetes management, in accordance with the WHO's global strategy on traditional medicine.