Hemoglobin A1c: a reliable and accurate test for diabetes care? A prospective study in Mexico

Objective: To compare the concordance correlation coefficient for HbAlc results in an in-field experience. Materials and methods: A prospective study in Monterrey, Mexico from April to August 2012 was conducted to evaluate the day-to-day clinical situation when measuring HbAlc. Blood samples from 38 consecutive patients were sent to seven local laboratories and one international reference laboratory. Results: Poor concordance was found in 4 out of 7 laboratories, moderate in 2 out of 7, and significant in just one. HbAlc values from three laboratories fluctuated more than 1% above or below the reference laboratory in more than 30% of cases, and more than 2% in 10%-20% of subjects. Conclusions: Standardized HbAlc measurement has not occurred worldwide. Physicians should be aware of this issue and be cautious of HbAlc guidelines on diabetes diagnosis or management until proper standardization programs are implemented.