Impact of Blood Sample Collection and Processing Methods on Glucose Levels in Community Outreach Studies

Glucose obtained from unprocessed blood samples can decrease by 5%–7% per hour due to glycolysis. This study compared the impact of glucose degradation on measured glucose values by examining two different collection methods. For the first method, blood samples were collected in tubes containing sodium fluoride (NaF), a glycolysis inhibitor. For the second method, blood samples were collected in tubes containing a clot activator and serum gel separator and were centrifuged to separate the serum and plasma 20 minutes after sample collection. The samples used in the two methods were collected during the same blood draw and were assayed by the clinical laboratory 2–4 hours after the samples were obtained. A total of 256 pairs of samples were analyzed. The average glucose reading for the centrifuged tubes was significantly higher than the NaF tubes by ？mmol/L ( ) or 4.2%. This study demonstrates the important role collection methods play in accurately assessing glucose levels of blood samples collected in the field, where working environment may be suboptimal. Therefore, blood samples collected in the field should be promptly centrifuged before being transported to clinical labs to ensure accurate glucose level measurements. 1. Introduction The childhood obesity epidemic has been accompanied by an increase in children with impaired fasting glucose, impaired glucose tolerance, metabolic syndrome, and type 2 diabetes [1, 2]. The diagnoses of these conditions in children depend on reliable blood glucose determinations. It is important to recognize that the preanalytical handling of blood samples intended for glucose measurement can influence the laboratory results [3]. When left unprocessed, glycolysis occurs in the cellular component of a blood sample and may consume 5%–7% of the sample’s glucose content per hour [4]. This is particularly relevant while conducting community or public health efforts, where the blood samples are collected in the field and several hours may elapse from time of collection to laboratory analysis. There are numerous publications detailing a variety of handling methods that can reduce loss of glucose [5]. The American Diabetes Association suggests prompt placement of blood samples in an ice slurry or immediate separation of plasma from blood cells can halt glycolysis [6]. However, such practice may not always be possible when transporting samples from the field to the clinical laboratory. A widely used technique involves the addition of NaF to blood tubes. NaF inhibits enolase, an enzyme in the glycolytic pathway. Although NaF has