This cross-sectional study included 1,301 female patients treated at Hunan Provincial People's Hospital between January 2021 and January 2023 without missing data. Participant inclusion criteria: (1) postmenopausal women (cessation of menstruation for more than 1 year); (2) Diagnosis of essential hypertension; (3) cooperation with the survey and signing of informed consent form. Exclusion criteria: (1) participants who had used medications that could impact their blood pressure and homocysteine levels; (2) Patients who are unable to accurately describe their own state, such as mental illness, speech problems, etc.

All study participants signed an informed consent form before taking part in the study, which was evaluated and approved by the Medical Ethics Committee of Hunan Normal University (No. 034/2017). After data collection, all participant information is kept anonymous and each participant is given a code. No names are ever published in any way.

Sample size calculations were based on the prevalence of H-type hypertension among hypertensive patients using a single population proportion sample size formula. According to the literature review, the proportion of H-type hypertension in the Chinese hypertensive population was 73% (3), and a minimum sample size of 1,250 cases was required for the study, assuming an α of 0.05, a β of 0.80 and a 95% confidence interval.

The data collection consisted of questionnaires, physical examination and laboratory tests. The questionnaire was administered by a uniformly trained investigator by face-to-face questioning, which included basic information, smoking history, drinking history, diet and physical activity.

Educational background was categorized into four groups: primary school and below, junior school, senior school, and college and above. Single or married were the two categories for marital status. Patients' level of regular activity was assessed based on how many times they worked out each week: 0 represented no exercise, 1–3 represented irregular exercise, and >3 represented regular exercise. We defined current alcohol intake as having at least two drinks per week and current smoking as continuously or cumulatively smoking one or more cigarettes per day for six months. The definition of covariates was informed by a previous questionnaire designed by the subject group for a cross-sectional survey of H-type hypertension (16).

Measurements of height, weight, waist circumference, and blood pressure are all part of a physical examination. A trained nurse used a conventional mercury sphygmomanometer to take three blood pressure readings at baseline, following a strategy that was developed from the American Heart Association's guidelines. A systolic blood pressure (SBP) ≥ 140 mmHg and/or a diastolic blood pressure (DBP) ≥ 90 mmHg were considered to be a diagnosis of hypertension (17). Patients with H-type hypertension were those who were diagnosed with essential hypertension and had a Hcy level >10 mol/L (18).

Within 24 h of admission, we took 5 ml of fasting venous blood and sent it to the Hunan Provincial People's Hospital's Department of Laboratory Medicine's fully automated biochemical analyzer to measure triglycerides (TG), fasting blood glucose (FPG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), alanine transaminase (ALT), serum cr (Scr) and estimated glomerular filtration rate (eGFR).

The values for glucose and triglycerides were converted from mmol/l to mg/dl. (multiplied by 18.020 and 88.545, respectively) (19). Triglyceride-glucose index was calculated as ln [triglycerides (mg/dl) × fasting glucose (mg/dl)/2] (20).

Categorical variables were presented as numbers (n) and percentages (%), and the χ2 test was used to compare group differences. Data for normally distributed continuous variables are expressed as mean ± standard deviation (SD), and t-tests were used to compare differences between groups. Data for continuous variables with skewed distribution were expressed as median (interquartile spacing), which was examined by the Mann-Whitney test. Before applying the tests, its normality was checked with the Kolmogorov–Smirnov test, and its homoscedasticity was checked with Levene's test. We utilized multivariable logistic regression models to examine the association between Tyg quartile subgroups and risk of H-type hypertension after adjusting for known possible confounders between TyG and H-type hypertension as well as for covariates at P < 0.05 in univariate analysis. We created three models: model 1 was unadjusted; model 2 included adjustments for age, BMI, educational background, exercise, smoking and drinking history; model 3: The variables LDL, BUN, and eGFR were subsequently added to model 2. We observed no significant covariance between these variables (all VIF < 3) (Supplementary Table S1). To investigate the form of the association between the TyG index and H-type hypertension, we also used a restricted triple spline with three nodes (5th, 50th, and 90th percentiles), each truncated at the highest and lowest 0.5% of the TyG index. To determine whether relevant factors (age, body mass index, eGFR, smoking, alcohol consumption, and exercise history) influenced the association between TyG index and H-type hypertension, we performed subgroup analyses in which an interaction term was added to the logistic regression model. For different definitions of H-type hypertension (Hcy levels ≥ 15 μ/L), we further performed sensitivity analyses to explore whether the association continued to exist. All statistical analyses were performed using SPSS 25.0 and R 4.1.2, and the study was conducted using a two-sided test for p-values, with p < 0.05 considered significant.

In this investigation, we examined 1,301 postmenopausal women who had essential hypertension. The individuals' median TyG index concentration was 8.761 mg/dl (interquartile range, 8.291–9.167), and their median age (interquartile range) was 56.0 (51.0–66.0) years. By hypertension status, Table 1 displays the participant baseline characteristics. This investigation revealed 634 (48.7%) patients with H-type hypertension overall, with statistically significant variations in TyG quartile subgroups. In comparison to controls, obesity, low education, insufficient physical activity, and alcohol use were all linked to an elevated risk of H-type hypertension. Additionally, individuals with H-type hypertension had significantly lower eGFR and significantly higher levels of TG, LDL, Scr, BUN and FPG (P < 0.05).

Table 2 illustrates the connection between the TyG index and H-type hypertension. When compared to the lowest quartile of the TyG index, the ORs (95% CI) for H-type hypertension were 2.3 (1.7–3.1) in univariate analysis for the highest quartile. In a logistic regression model (model 3) adjusted for a number of confounders (age, BMI, educational background, exercise, smoking history, drinking history, LDL, BUN, eGFR), higher TyG index remained significantly associated with increased risk of H-type hypertension. The fully adjusted OR (95% CI) for the risk of HHT in quartile 4 vs. quartile 1 was 2.0 (1.4–2.9; P < 0.001). The TyG index was also examined as a continuous variable. According to model 3, postmenopausal women's chance of developing H-type hypertension increased by 0.6 (95% CI: 1.3–2.0; P < 0.001) per unit increase in TyG index. The association between TyG index and H-type hypertension remained significant even after adjustment for potential confounders.

The TyG index and H-type hypertension were shown to be correlated linearly by restricted cubic spline regression models (P for linear trend < 0.001; Figure 1). The reference point is the cutoff value of the first quartile (8.291 mg/dl), and the nodes are located at the TyG index's horizontal range at the 5th, 50th, and 90th percentiles. The trend test (P < 0.001) between Tyg quartiles in the unadjusted model and the two adjusted models further illustrates the linear relationship, as shown in Table 2. The findings imply that a persistent rise in the TyG index increases the chance of postmenopausal women acquiring H-type hypertension.

With regard to age, BMI, smoking history, drinking history, exercise, eGFR, subgroup analysis revealed that TyG index was positively associated with H-type hypertension. Futhermore there were no significant interactions between TyG index and these potential risk factors of interest for H-type hypertension (P > 0.05 for all interactions) (Figure 2).

As shown in Table 3, the results were stabilized (OR = 1.4; 95% CI, 1.1–1.9; P = 0.008) by sensitivity analyses for different definitions of H-type hypertension (Hcy levels ≥ 15μ/L).