International clinical harmonization of glycated hemoglobin in Japan: From Japan Diabetes Society to National Glycohemoglobin Standardization Program values

Abstract

In 1999, the Japan Diabetes Society (JDS) launched the previous version of the diagnostic criteria of diabetes mellitus, in which JDS took initiative in adopting glycated hemoglobin (HbA1c) as an adjunct to the diagnosis of diabetes. In contrast, in 2009 the International Expert Committee composed of the members of the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) manifested the recommendation regarding the use of HbA1c in diagnosing diabetes mellitus as an alternative to glucose measurements based on the updated evidence showing that HbA1c has several advantages as a marker of chronic hyperglycemia2–4. The JDS extensively evaluated the usefulness and feasibility of more extended use of HbA1c in the diagnosis of diabetes based on Japanese epidemiological data, and then the ‘Report of the Committee on the Classification and Diagnostic Criteria of Diabetes Mellitus’ was published in the Journal of Diabetes Investigation5 and Diabetology International6. The new diagnostic criterion in Japan came into effect on 1 July 2010. According to the new version of the criteria, HbA1c (JDS) ≥6.1% is now considered to indicate a diabetic type, but the previous diagnosis criteria of high plasma glucose (PG) levels to diagnose diabetes mellitus also need to be confirmed. Those are as follows: (i) FPG ≥126 mg/dL (7.0 mmol/L); (ii) 2‐h PG ≥200 mg/dL (11.1 mmol/L) during an oral glucose tolerance test; or (iii) casual PG ≥200 mg/dL (11.1 mmol/L). If both PG criteria and HbA1c in patients have met the diabetic type, those patients are immediately diagnosed to have diabetes mellitus5,6.