I have researched individually herbs recommended in Ayurveda and TCM for diabetes healing. The scientific evidence is highest in the following herbs. I am listing their botanical names below. Supplements use different local names for each of these plants. It is, therefore, best to identify these from universally accepted botanical names:
Ayurveda:
Gymnema sylvestre, Trigonella foenum-graecum, Eugenia jambolana, and Curcuma longa
TCM
Atractylodes macrocephala, Codonopsis pilosula, Dioscorea opposita, Flos lonicerae, and Pueraria lobata
There is a lot of anecdotal evidence in favor of supplements containing these herbs. However, human clinical trials have not been conducted to the satisfaction of regulatory bodies. Consumption of supplements, therefore, should only be done in consultation with your diabetologist. Unfortunately, there exists an unnecessary rivalry and mutual dislike between physicians who practice modern and herbal medicine. The rivalry is to the detriment of consumers who are patients.
Additional reading:
Natural Solutions for Diabetes