RH blood groups and diabetic disorders: Is there an effect on glycosylated hemoglobin level?

Recent cloning of RH genes has elucidated their structure, suggesting that RH proteins are part of an oligomeric complex with transport function in the erythrocyte. This observation prompted us to investigate a possible relationship between the RH system and the glycosylated hemoglobin level (Hb A(1c)) in diabetes. This compound is considered an important indicator- of glycemic control in diabetic disorders. We studied 278 subjects with non-insulin-dependent diabetes mellitus (NIDDM) from the population of Penne, Italy. Glycemic and glycosylated hemoglobin (Hb A(1c)) levels are associated with RH phenotype. Glucose and Hb A(1c) levels are increased in DCcEe subjects and decreased in ddccee subjects as compared to the mean values for other genotypes. Sex, age at onset of disease, duration of disease, and age of patients were also considered. Correlation analysis suggests that these variables influence glycemia directly and Hb A(1c) indirectly. The RH system, on the other hand, seems to influence the Hb A(1c) level directly. Preliminary data on 53 children with insulin-dependent diabetes mellitus (IDDM) from Sardinia seem to confirm the relationship between RH and Hb A(1c) observed in NIDDM. Since glycosylated hemoglobin is found inside red blood cells, the relationship between RH genetic variability and Hb A(1c) level suggests that RH proteins may influence glucose transport through red cell membrane and/or hemoglobin glycation.