How are VDR and blood sugar related?

The relationship between VDR (vitamin D receptor) and blood sugar is supported by mechanistic and observational evidence, but effect sizes are modest. VDR polymorphisms (e.g., rs2228570, rs1544410) alter vitamin D signaling, which influences insulin secretion and sensitivity. Vitamin D acts via VDR on pancreatic beta cells and peripheral tissues. Epidemiological studies link low vitamin D levels to higher type 2 diabetes risk. However, randomized controlled trials do not consistently show that vitamin D supplementation improves glycemic control. Genetic variation in VDR accounts for only a small fraction of blood sugar variance. Direct-to-consumer DNA tests reporting VDR variants have limited predictive power for individual glucose regulation. Lifestyle factors—fiber intake, physical activity, sleep—are far more impactful. Evidence grade: human-moderate (observational studies, meta-analyses). No specific sources from the provided context.