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March 6, 2004

Blood Tests and Insulin Injections, Other

Question from Fort Mill, South Carolina, USA:

Can you tell me if the standard normal blood sugar range 80-120 mg/dl [4.4-6.7 mmol/L] is in reference to whole blood or plasma? My new glucometer is reading about 15 points higher than my old one and they are both set for plasma, so I would like to know how far off I could be from normal. Should my goal range really be 90-130 mg/dl [5.0-7.2 mmol/L] in plasma readings?


From: DTeam Staff

The normal blood sugar range of 80-120 mg/dl [4.4-6.7 mmol/L] is based on whole blood assays and the average correction for serum (or plasma) is about +14 percent, which would give you a new range of approximately 90-135 mg/dl [5.0-7.5 mmol/L] of serum or (plasma). The reason for expressing levels as serum (or plasma) is that clinical laboratories usually now measure glucose in centrifuged blood samples in automated instruments that do multiple assays that require serum (or plasma).