We examined the relationships between 4 glycated protein assays and home blood glucose monitoring (HBGM) in 26 children with poorly-controlled insulin-dependent diabetes mellitus (IDDM) during a period of improved management. At 2 week intervals for 6 visits (12 weeks in total), HBGM records were collected and a blood sample was obtained for measurement of glycated proteins and glucose. Assays included glycated hemoglobin (GHb) and glycated serum proteins (GP) by boronate affinity chromatography, hemoglobin A1C by PolyCAT A high performance liquid chromatography (HAC) and fructosamine (FA). All 4 glycated protein levels declined significantly over the 12 week period. Significant correlations between the glycated proteins and HBGM were observed over 2 week intervals. None of the 4 assays were affected by the glucose level in the sample. Changes in mean HBGM readings over 2 week intervals were correlated with both FA and GP with wide prediction intervals. Over cumulative 2 week intervals, which may more accurately reflect longitudinal trends, all 4 glycated proteins were correlated with mean HBGM readings. At each cumulative interval, GHb and GP showed the largest variation with MBG, while FA showed the least variation with MBG. Our data indicate that of the 4 assays tested, FA has limited clinical values as compared to other glycated protein assays, whereas assays based on boronate affinity chromatography (GHb and GP) provide the most useful clinical indicators of short-term changes in glycemic control. The clinical utility of a new HPLC method for determination of glycated hemoglobins is also demonstrated.