Caveats regarding the use of HbA_1c for prediction of mean blood glucose. Reply to Chalew S, Hempe JM [letter]

Excerpt

Chalew and Hempe [1] respond to our study in which we demonstrate, in a relatively small group of patients with type 1 and type 2 diabetes and non-diabetic individuals, a high degree of correlation between carefully measured mean glucose levels over a 3 month period and HbA_1c at the end of the 3 months [2]. They object to our suggestion that HbA_1c should be ‘used universally to adjust therapy’ [1]. (In fact, we didn’t suggest that HbA_1c be used universally for this purpose, although we believe it to be appropriate; rather, we only stated the fact that HbA_1c ‘is the basis of treatment guidelines, and is used universally to adjust therapy’ [2]). Chalew and Hempe further propose that the ‘between-patient variation in the relationship between HbA_1c and MBG (mean blood glucose)’ precludes its universal use to adjust therapy. …