To evaluate the clinical significance of HbAC in diabetics, we investigated the relationships between hemoglolbin A,C blood suger, urinie suga, and serum lipid in 70 diabetics. The results are summarized as follows: 1) The mean HbA,C levels in diabetics was significantly higher than that of normal subjects (p<0.001) 2) The HbAC levels in diabetics was not related to the duration of disease and therapy(p>0.05.), 3) ln diabetics, the positive correlations were observed between HbC Ievei and PBS,PP 2hr sugar and 24 hours urine sugar, respectively (r=0.63,0.67,0.59. P<0.001). 4) The HbAC levels was not related to the complication of diabetics, but highger level in diabetic ketoacidosis. 5) The postive correlations were not observed between HbAC levels and blood lipid including triglyceride, cholesterol and beta-lipoprotein(r=0.09,0.11,0.13., p>0.05) This resuIt suggest that HbAC measurement is a simple, rapid and objective procedure to ascess diabetic control and may serve as a screening test for uncontrolIed dliabetics.