Glycosylation of variant hemoglobins in normal and diabetic subjects

The extent of in vivo glycosylation of variant hemoglobins was examined in individuals with S-, C-, and D-trait. Chromatographic estimates of glycosylation for nondiabetic individuals with S-trait were significantly lower than those for nondiabetic black subjects with normal hemoglobin (P < 0.001). However, chemical determinations of glycosylation (thiobarbituric acid or TBA technique) were similar for these groups (P > 0.10). The chromatographic elution pattern of hemoglobin S (HbS) was determined, and on this basis an adjustment procedure was performed for chromatographic data. A regression line was calculated for the relationship between chromatographic and colorimetric estimates of glycosylated hemoglobin in S-trait individuals with and without diabetes. The slope of this line was significantly different (P < 0.001) from that for the relationship in individuals with normal hemoglobin. However, after adjustment of chromatographic values from S-trait individuals, the slopes were similar (P < 0.10). Findings from individuals heterozygous for HbC and D were similar to those for individuals with S-trait. These data indicate that the extent of glycosylation of HbS, C, and D is similar to that of HbA in both the normoglycemic and hyperglycemic range. The TBA technique is the most direct method for determining the extent of glycosylation in individuals with HbS, C, or D. However, adjustment of column chromatographic values is feasible.