There is currently very little research regarding curcumin’s effects on blood sugar levels.
One randomized controlled trial (RCT) found that supplementation with 500 mg of curcumin three times daily for 12 weeks significantly decreased fasting blood glucose levels in women with polycystic ovary syndrome (PCOS) compared to a placebo but had no effect on insulin levels or insulin resistance.[1] However, another RCT that included individuals with metabolic syndrome and used nanomicellar curcumin did not find any improvements in either fasting blood glucose or insulin levels.[2]