This protocol provides instructions for drawing, processing and storing blood for the hemoglobin A1c assay according to the National Health and Nutrition Examination Survey (NHANES) methods. Toolkit users are referred to the National Glycohemoglobin Standardization Program for standardized laboratory assays. The Diabetes Working Group notes that that there are now point of care instruments for testing Glycosylated hemoglobin that may provide an alternative to the protocol listed here.