Your three-month blood-sugar average drops about 0.4 points
Across twenty randomised trials in 1,761 people, berberine cut HbA1c, the three-month average of blood sugar, by roughly 0.4 percentage points against placebo.
What the study found
Berberine cuts long-term blood sugar by about 0.4 percentage points
Long-term blood sugar does fall, just not far. Across twenty randomised trials in 1,761 people, berberine cut HbA1c, the three-month average of blood sugar, by roughly 0.4 percentage points against placebo, and the largest single trial of 409 people landed in the same place.
The caveat · An average across mixed regimens
The bigger effects reported in women, in people already diagnosed, and in Asian populations each rest on a handful of trials, few enough that ordinary chance could produce them. Doses and trial lengths varied widely, so 0.4 points is an average across regimens rather than the result of any one of them. Berberine caused more stomach and bowel upset than placebo in the large trial.