Dr. Randie Little, PhD is Co-Director of the Diabetes Diagnostic Laboratory (DDL) and Network Coordinator for the National Glycohemoglobin Standardization Program (NGSP). The DDL, is the site of the NGSP, an international program for standardization of HbA1c which is the most important test used to assess glycemic control in patients with diabetes. The NGSP maintains a laboratory network with reference method results that are based on landmark clinical trial data. The program certifies manufacturer methods for HbA1c and also certifies and monitors laboratories doing large studies and clinical trials where measurement of HbA1c is a key variable. Proficiency testing, primarily through the College of American Pathologists, is used to evaluate progress toward improved comparability of results among laboratories. The NGSP network assigns values to the accuracy based CAP HbA1c survey. Related research includes examination of stability of HbA1c and interferences (e.g. from Hb variants) with different assay methods. Standardization of c‐peptide is also in progress at the DDL. For c‐peptide, as with HbA1c, purified or processed material shows significant matrix effects and cannot be used for calibration. The c‐peptide program includes the use of single donor and pooled serum specimens for use by manufacturers in the calibration of their assays. The DDL has established an LS/MS reference method for c‐peptide (coordinated with the National Metrology Institute of Japan and Albert Einstein College of Medicine as well as a complete traceability chain for C-peptide.
- Glycated hemoglobin (HbA1c) methodology and Interferences
- Standardization of glycated hemoglobin (HbA1c) measurement
- Mechanisms of glycation and clinical applications
- In Vitro models of protein glycation
- Use of glycated hemoglobin and glycated plasma protein measurements for diabetes screening and diagnosis
- Standardization of insulin and c-peptide measurement
Areas of Expertise
- HbA1c methodology and Interferences
- Standardization of HbA1c, insulin, and c‐peptide measurements
Education & Training
Biology, Florida State University, Tallahassee, FL
- Rohlfing CL, Parvin CA, Sacks DB, Little RR. Comparing Analytic Performance Criteria: Evaluation of HbA1c Certification Criteria as an Example. Clin Chim Acta 2014;433:259-263.
- Little RR, La’ulu SL, Hanson SE, Rohlfing CL, Schmidt RL. Effects of 49 Different Rare Hb variants on HbA1c Measurement in Eight Methods. J Diab Sci & Tech 2015;9:849-856.
- Weykamp C, John G, Gillery P, English E, Ji Linong J, Lenters-Westra E, Little RR, Roglic G, Sacks D, Takei I. Investigation of two models to set and evaluate quality targets for HbA1c: Biological variation and Sigma-metrics. Clin Chem 2015; 61:752-9.
- Klonoff DC, Lias C, Beck S, Parkes JL, Kovatchev B, Vigersky RA, Arreaza-Rubin G, Burk RD, Kowalski A,Little R, Nichols J, Petersen M, Rawlings K, Sacks DB, Sampson E, Scott S, Seley JJ, Slingerland R, Vesper HW. Development of the diabetes technology Society blood glucose monitor system surveillance protocol. JDST, 2015;October.DOI: 10.117/1932296815614587
- Little RR, Rohlfing CL. Assessing quality from an accuracy-based HbA1c proficiency survey. Clin Chem Lab Med 2016;54:e75-6.
- Rastogi MV, Ladenson P, Goldstein DE, Little RR. Quality of HbA1c Measurement in Trinidad and Tobago. J Diab Sci & Tech 2016;10:768-71.
- C. Rohlfing, S. Hanson, C. Weykamp, C. Siebelder, T. Higgins, R. Molinaro, P.M. Yip, R.R. Little. Effects of hemoglobin C, D, E and S traits on measurements of hemoglobin A1c by twelve methods. Clin Chim Acta 2016;455:80-3.
- Kuanysh Kabytaev, Shawn Connolly, Curt L. Rohlfing, David B. Sacks, Alexander V. Stoyanov, Randie R. Little. Higher degree of glycation of hemoglobin S compared to hemoglobin A measured by mass spectrometry: Potential impact on HbA1c testing. Clin Chim Acta 2016;458:40-3.
- Rohlfing C, Connolly S, Hanson S, Higgins T, Little R. Validation of the use of Trinity Biotech ultra2as a comparative method for Hemoglobin A1c measurements in the presence of HbE and HbD-Punjab traits. Clin Chem 2017; 63:608-10.
- Little RR, Wielgosz RI, Josephs R, Kinumi T, Takatsu A, Li H, Stein D, Burns C. Implementing a Reference Measurement System for C-peptide: Successes and Lessons Learned. Clin Chem 2017;63:1447-56.
- Little RR, Kinumi T, Connolly SM, Kabytaev K. Implementing a Reference Measurement System for C-peptide: an Addendum. Clin Chem 2017: 63:1904-5.