Venous blood glucose is typically how much lower than capillary or arterial blood?

• A. 0%
• B. 5%
• C. 10%
• D. 15%

Answer: (B)

Glucose is delivered to tissues via arterial blood and then taken up as it passes through tissues. Because cells extract some glucose on the way back in the venous system, venous glucose ends up a bit lower than arterial or capillary glucose. In healthy individuals under typical conditions, this difference is about 5%, so venous levels are roughly five percent lower. For example, arterial or capillary glucose around 100 mg/dL would be about 95 mg/dL in venous blood. Capillary readings often track arterial values more closely, which is why they’re used for quick monitoring. The 5% figure reflects normal physiologic extraction and is smaller than you’d see only in special states of metabolism or measurement.