Introduction This study aimed to determine the effectiveness of mustard green leaf decoction as an adjunct to drug treatment in controlling blood glucose among Filipinos with type 2 diabetes mellitus.

Methods Participants were randomly assigned to receive mustard decoction or a placebo solution for eight weeks on top of their oral anti-hyperglycemic medication. Fasting blood sugar and complete blood counts were determined at baseline, Week 4 and Week 8, and compared within and across the two groups. 

Results There was a decreasing trend in the blood sugar in the mustard green group while the opposite was noted in the placebo group. The mean FBS levels of the mustard green group were significantly lower than that of the placebo group at the Week 8 determination (6.10 vs 8.69 mmol/L, p=0.0004). The decrease in blood sugar level on the eight week in the mustard green group was significant compared with the baseline level (p=0.008).

Conclusion This study had demonstrated that the intake of Brassica juncea decoction can significantly decrease blood sugar level among type 2 diabetics compared to metformin alone.