A Randomized Controlled Study of Dose-finding, Efficacy, and Safety of Mulberry Leaves on Glycemic Profiles in Obese Persons with Borderline Diabetes

Objectives: Mulberry (Morus alba L.) leaves have been used in traditional medicine for treating hyperglycemia. However, there remains difficulties in the implementation of mulberry leaves in evidence-based practice. The aims of this study were to examine the optimal dose of 1-deoxynojirimycin (DNJ) in mulberry leaves and to determine the efficacy and safety of mulberry leaves in glycemic control in obese persons with borderline diabetes.

Design: First, healthy adults were recruited into the dose-finding study and randomly allocated to ingest sucrose solution concurrently with mulberry leaf powder at weights equivalent to 0 (control), 6, 12, and 18 mg of DNJ. Postprandial glucose and undesirable effects were evaluated. Second, obese persons with borderline diabetes were randomly assigned into the mulberry-leaves treatment group (12 mg of mulberry DNJ three times daily) and the control group in the 12-week prospective study. Blood glucose and insulin as well as adverse effects were determined.

Results: Twelve mg of mulberry DNJ was the minimum effective dose attenuating postprandial hyperglycemia. Mulberry leaves decreased fasting plasma glucose (FPG) by 3.86 ± 5.99 mg/dL (p = 0.002) and glycated hemoglobin (HbA1c) by 0.11 ± 0.22 % (p = 0.011) when compared with the baseline levels. Improvement in glucose tolerance was not observed. Furthermore, mulberry leaves tended to ameliorate insulin resistance (p = 0.057). Adverse events of mulberry leaves commonly found in this study were gastrointestinal symptoms including bloating, flatulence, and loose stools.

Conclusion: Mulberry leaves possessed favorable effects on glycemic profiles without serious side effects.