Level I Laboratory Certification includes both yearly certification of traceability to the DCCT and a quarterly monitoring component to insure stability throughout the year. This type of certification is recommended for large laboratories that are involved in research studies or clinical trials where long term precision of glycated hemoglobin measurement is critical, i.e. where a small shift in glycated hemoglobin results could effect the final outcome of a trial or research study. The certification protocol for Level I Laboratory Certification will be the same as followed for manufacturer method certification as outlined in section C. However, the certification criteria are more stringent; the 95% CI of the differences between methods must fall within ±0.75% GHB.

Laboratories are awarded Certificates of Traceability for successfully completing fresh sample comparisons for the specific method, reagent lots, calibrator lots and instrumentation used. Traceability to the DCCT applies only to results from fresh or fresh frozen blood samples. Analysis of processed (e.g. lyophilized) material may be subject to matrix effects and any comparisons to the DCCT using results from processed specimens should be made with caution.
Level 1-certified laboratories are also monitored on a quarterly basis using 10 fresh samples, analyzed in two separate runs on two separate days. Monitoring criteria are identical to those used for network lab monitoring; mean difference between laboratories <0.35% HbA1c, SD of the difference in sample replicates < 0.229. Level 1 laboratories must submit quarterly monitoring data within two weeks of receipt of monitoring specimens and pass the criteria in order to maintain their certification status.

Level 1-certified laboratories must complete analysis of quarterly monitoring samples in order to maintain certification. If a Level 1 laboratory either does not pass the monitoring criteria, or fails to send in data, for two consecutive quarters, the laboratory will be removed from the NGSP Certified Level 1 Laboratory list. If the laboratory then passes the NGSP monitoring criteria in a subsequent quarter, they will be placed back on the Certified Level 1 Laboratory list.