Glycation Index Is Not an Independent Predictor of the Risk of Microvascular Complications in the Diabetes Control and Complications Trial: Diabetes 56:1913–1921, 2007

Recently, Lachin et al. (1) published a reassess-ment of the role of the hemoglobin glycationindex (HGI) for prediction of microvascularcomplications in the Diabetes Control and Com-plications Trial (DCCT). They conclude that HGI is not a useful predictor because it is not statistically independent of A1C. Their analysis was based on work from a prior publication of ours, in which we came to the conclusion that between-patient biological variation in A1C, as quan-tified by HGI, along with mean blood glucose (MBG) were both important predictors of complications (2). We believe that the difference in conclusions is due to a difference in the research question being addressed by our two respec-tive groups. Our group has previously shown that there are substan-tial differences in the level of A1C between patients at any given MBG that are nonrandom and consistent over time (2–3). The impact of these between-patient differences o