EFFECT OF GLYCEMIC CONTROL ON VITAMIN-B-12 METABOLISM IN DIABETES-MELLITUS

To determine the effect of glycemic control on vitamin B-12 (B-12) met abolism in diabetes mellitus, we studied B-12 metabolism in 19 diabeti c patients with poor glycemic control and 15 normal individuals. The d iabetic patients had significantly higher total B-12 binding capacity (3303 +/- 963 pg/ml), higher serum B-12 levels (1173 +/- 503 pg/ml) an d unsaturated B-12 binding capacity (2131 +/- 902 pg/ml) when compared with the normal controls, but there was no difference in R-binder lev els and the B-12 binding ratio between the two groups. During a 2-week admission to establish glycemic control, the fructosamine levels in t he diabetic patients decreased from 556 to 428 mu mol/l and the total B-12 binding capacity as well as unsaturated B-12 binding capacity wer e significantly improved to the normal range (P < 0.01), but serum B-1 2 levels, R-binder levels and the B-12 binding ratio were not changed. There was a significant association between serum fructosamine levels and the total B-12 binding capacity in poorly controlled diabetic pat ients and the decrease of fructosamine was correlated significantly wi th the change of total B-12 binding capacity and serum B-12 levels in diabetic patients. These results indicate the effects of glycemic cont rol on B-12 metabolism in diabetes mellitus.