Background & Objectives: The KCNJ11 E23K (rs5219) polymorphism in Lembak ethnicity may be a basic predisposing factor for DM heritability. Diagnosing of DM and grouping people at risk of DM confirmed by examining HbA1c. The research to identify the polymorphism of KCNJ11 E23K (rs5219) gene and its relationship with the concentration of HbA1c in the first generation of Lembak ethnicity in Bengkulu. Methods: The cross sectional study of 54 samples. The detection of single nucleotide polymorphism (SNPs) achieved through the Polymerase Chain Reaction Restriction Fragment Length Polymorphisms (PCR-RFLP) technique. The measurement of HbA1c concentrations performed using the boronate affinity method. Results: Identification frequencies of KCNJ11 E23K polymorphism in first generation of DM showed that genotypes EE, EK, and KK were respectively 55.6%, 29.6% and 14.8%. In the non-DM first generation showed that genotypes EE, EK and KK were respectively 44.4%, 25.9%, 29.6%. There was no statistically significant disparity observed in the KCNJ11 E23K genotype across the groups (p = 0.420). Meanwhile, there was no statistically significant relationship observed between the KCNJ11 E23K polymorphism and HbA1c concentration in both the first generation DM (p=0.681) and non DM (p=0,882) groups. Conclusions: This study showed no significant difference in genotype allocation of the KCNJ11 E23K (rs5219) polymorphism between the first generation of DM and non-DM in Lembak Ethnicity. This study also showed no linked between the KCNJ11 E23K (rs5219) polymorphism and HbA1c concentrations in the first generation of Lembak Ethnicity, Bengkulu.