Conundrum of elevated HbA1c and hypoglycemia -: A rare cause

A white diabetic patient on insulin therapy presented with recurrent hypoglycemia despite very high glycosylated hemoglobin (HbA(1c)) values. Hemo- globin (Hb) variants, chemically modified Hb, and abnormalities of red cell turnover cause errors in HbA(1c) measurement. Widely prevalent Hb variants affecting HbA(1c) estimation include HbS and HbC in African Americans, HbE in southeast Asians, and carbamyl-Hb in uremic patients. In addition, there are at least 893 other Hb variants as of 2005, many of which affect HbA,c estimation. HbA,c values are also affected by methodology of estimation. Our patient had HbJ, which is rare amongst whites. The relationship between HbA(1c) values and mean plasma glucose allows estimation of expected HbA(1c). Significant discrepancy between expected and measured HbA(1c) should be evaluated. Considering Hb variants, evaluating for the same and estimating HbA(1c) with the appropriate method under such circumstances are described. Numerous new or rare Hb variants will be diagnosed if suspicion is appropriately entertained.