Berberine vs Magnesium
for blood sugar
Stronger evidence: Berberine
Stronger effect: Berberine
Safety: Berberine has the more serious interaction profile (moderate vs minor).
For blood sugar, Berberine has the stronger evidence grade.
Berberine
grade B moderate certainty
lowers fasting glucose and HbA1c; GI side effects common
500 mg ×3/day, adults with elevated glucose
Magnesium
grade C moderate certainty
modest improvement in insulin sensitivity / fasting glucose, mainly in deficiency or diabetes
250–400 mg/day, adults with insulin resistance
sources: PMID:00000030 · PMID:42197052