There are a few Ayurvedic herbal formulas that the NIH have tested and shown efficacy. I know one of them is at mapi.co and Himilaya has GlucoCare and I know there are others.
Magnesium is pretty vital. I would test thru TraceElements.com
Magnesium Chloride is probably a better choice than mag taurate or UltraMag by Source Naturals.