Generally, the blood sugar of the blood capillaries measured by finger or ear blood on the market is slightly higher than the venous blood sugar.
But be aware that it will be slightly affected when cold, edema and vasospasm. In recent years, my country's Changchun has been able to produce blood glucose test strips.
Since the 1990s, non-damaging blood glucose monitors have been developed abroad, which use computerized near-infrared rays to measure the changes in absorption through the skin surface. It can measure 2.22-22.2 millimoles/liter within 5 seconds (40～ 400 mg/dL) blood sugar.