A very informative video on resveratrol dosage breakdown.
I have never noticed any benefit from taking resveratrol but I dug it out of my pill collection and started a lower dose (<500mg) every other day to monitor long-term progress. 50 -100mg may be the target depending on your weight.
I'm a fan of anything safe purported to lower A1C and increase longevity. A big takeaway is that you may save your money if you've been taking a higher dose as recommended by Dr. Sinclair, which may be the reason I noticed no benefit in the past.