Is CYP2D6 useful for blood sugar?

CYP2D6 is a drug-metabolizing enzyme with no direct, clinically relevant role in blood sugar regulation. Its genetic variants are used in pharmacogenetics to predict metabolism of medications such as antidepressants, beta-blockers, and opioids. A link to fasting glucose, insulin resistance, or diabetes risk is not established in current evidence. Indirect effects via drugs that influence glucose metabolism are theoretically possible but insufficiently supported. Direct-to-consumer tests often overstate the clinical utility of such markers. For blood sugar assessment, established parameters like HbA1c, fasting glucose, or polygenic risk scores for type 2 diabetes are far more informative. The evidence for CYP2D6 in this context is weak to unclear.