Nu Zhen Zi (Fructus Ligustri Lucidi) is a Chinese herb. There's little research from Western countries regarding the use of ligustrum. A Chinese study has found ligustrum to be useful in lowering blood sugar in mice. Whether this same effect occurs in humans in not clear.

Ligustrum Research
[Studies on immunomodulatory function of polysaccharide of Fructus Ligustri Lucidi]
Zhongguo Zhong Yao Za Zhi. 1999 Nov;24(11):691-3, 704.
To explore the immunomodulatory mechanism of Chinese medicine Fructus Ligustri Lucidi and to find its efficient material base. METHOD: The effects of ligustrum on the immunoactivity of mouse speen lymphocyte were studied in vitro or vivo by means of MTT. RESULT: Ligustrum could obviously promote the speen lymphocyte proliferation in normal mice and mice with Yin-deficiency selected by injection with adrenocorticortropic hormone. CONCLUSION: Ligustrum has an immunomodulatory function for both normal mice and mice with Yin-deficiency.

[Hypoglycemic effect of fructus Ligustri Lucidi]
Zhongguo Zhong Yao Za Zhi. 1992 Jul;17(7):429-31, 447.
The decoction of Fructus Ligustri Lucidi 15.30 g/kg ig for 10 days significantly decreased the blood glucose level in normal mice. Ligustrum 30 g/kg before or after the treatment of alloxan also decreased the blood glucose level in alloxan diabetic mice. The elevation of blood glucose level induced by adrenaline or glucose was antagonized by ligustrum.