Essential hypertension (EH) is commonly accompanied by a dysfunction of glucose metabolism. Glucokinase (GCK) is a key enzyme involved in glucose metabolism. The aim of the present study was to investigate whether GCK gene-body methylation contributed to the risk of EH. A total of 47 patients with EH and 47 age-matched controls were recruited for methylation research in the current study. GCK gene-body methylation was measured using bisulphite pyrosequencing technology. DNA methylation levels were closely correlated among CpG1, CpG2 and CpG3 (r>0.70; P<0.001), in contrast with a weaker correlation between CpG4 and the preceding three CpGs (r<0.3 or r=1; P>0.05). Significantly lower CpG13 methylation (cases vs. controls, 49.13 ± 5.72 vs. 53.49 ± 7.53%; adjusted P=0.006) and significantly higher CpG4 methylation (cases vs. controls, 46.34 ± 6.48 vs. 34.74 ± 12.73%; adjusted P=0.002) were observed in patients with EH. The present study indicated that aberrant methylation of the GCK gene body was significantly associated with the risk of EH in the population assessed. The discrepancies between CpG1‑3 and CpG4 methylation may suggest distinct roles for each of them in the determination of the risk of EH.