Elevated glycosylated hemoglobin levels and its interactive effects on hypertension risk in non-diabetic population: a cross-sectional survey in China

Background Abnormal glucose metabolism have been suggested to be involved in the development of hypertension. The present study aimed to investigate the associations and potential interactions of hemoglobin A1c (HbA1c) with other factors on the risk of hypertension among Chinese non-diabetic adults. Methods As a cross-sectional survey, the current work provided questionnaire survey, anthropometric tests and biochemical measure for each of the eligible participants. The HbA1c levels were quantified and grouped by quartiles. The correlation between HbA1c and hypertension risk in non-diabetic were investigated by univariate and multivariate analyses. For evaluating the interactive effects, the parameters of Relative Excess Risk due to Interaction (RERI), Attributable Proportion due to Interaction (AP) and Synergy Index (SI) were calculated, respectively. Results In the current study, 1462 non-diabetic subjects were enrolled. Totally, the prevalence of hypertension was 22.4% (n=327) in the individuals without diabetes. When the HbA1c levels were grouped by quartiles, it was revealed that the prevalence of hypertension substantially elevated across groups ( P for trend <0.001). In the multivariable logistic regression analyses, in comparison with the first quartile of HbA1c, the normalized OR for hypertension risk were 1.90 (95% CI:1.28-2.80) for the highest quartile. Besides, the ROC curve analysis indicated that the best threshold of HbA1c as the predictor for hypertension risk was 4.95 in non-diabetic subjects, with the AUC of 0.60 (0.58-0.63). Eventually, it was demonstrated from the interactive effect analysis that the HbA1c significantly interacted with abdominal obesity (RERI: 1.48, 95% CI: 0.38- 2.58; AP: 0.37, 95% CI: 0.14-0.60 and SI: 1.96, 95% CI: 1.06-3.62) and family history of hypertension (AP: 0.37, 95% CI: 0.05-0.70) on the risk of hypertension in non-diabetic participants. Conclusion The risk of hypertension was aggravated by the up-regulated HbA1c in an independent and synergistic manner with abdominal obesity and family history of hypertension in Chinese subjects without diabetes.