Objective  To explore the correlation between triglyceride glucose body mass index (TyG-BMI) and nocturnal ambulatory blood pressure parameters in nocturnal hypertension (NH) population.

Methods  A cross-sectional study design was adopted. A total of 1 301 patients with NH attending the Hypertension Department of TEDA International Cardiovascular Disease Hospital between January 2020 and March 2023 and the Hypertension Department of Tianjin Kanghui Hospital between September 2023 and April 2025 were selected as the study subjects, and the patients' data were collected and the TyG-BMI was calculated, and patients were grouped into quartiles according to TyG-BMI. A generalised linear model was applied to analyse the association between TyG-BMI groups and nocturnal ambulatory blood pressure parameters. Stratified analyses were conducted according to age, gender, smoking status, alcohol consumption and enrollment period. A restricted cubic curve (RCS curve) was drawn to analyse the correlation between TyG-BMI and the occurrence of target organ damage in patients with NH.

Results  The mean age of the total population was (47.75±13.55) years old, and the mean TyG-BMI was 243.17±42.31. The differences of the mean nocturnal systolic blood pressure, mean nocturnal diastolic blood pressure, and mean nocturnal heart rate among the 4 groups were statistically significant (P＜0.05). The results of the generalised linear model showed that, after correcting for confounders, compared with the first quartile group, the nocturnal systolic blood pressure, nocturnal diastolic blood pressure, and nocturnal heart rate were higher in the highest quartile group of the TyG-BMI by 5.14 mmHg (95%CI: 2.65 to 7.62, P＜0.001), 3.99 mmHg (95%CI: 2.18 to 5.80, P＜0.001), and 2.46 beats/min (95%CI: 1.06 to 3.85, P＜0.001). Sensitivity analyses were conducted after excluding individuals aged ≥ 60 years (n=1 014) and those with diabetes (n=1 109), yielding results consistent with the primary analysis. The results of subgroup analyses showed that there was an interaction between different subgroups of TyG-BMI and age, gender, smoking and alcohol consumption (all P＜0.05). In the ＜45-year-old and female populations, the nocturnal systolic blood pressure was more significantly elevated in the higher tertile groups of TyG-BMI, which were 7.11 mmHg (95%CI: 3.78 to 10.43) and 8.93 mmHg (95%CI: 4.29 to 13.56), respectively. Restricted cubic plots showed a nonlinear correlation between TyG-BMI (P_overall=0.017, P_nonlinear=0.011) and risk of target organ injury in the NH population.

Conclusion  In NH patients, TyG-BMI showed a positive correlation with nocturnal ambulatory blood pressure levels. Compared with the first quartile, the increase in mean nocturnal systolic blood pressure was greater in the highest TyG-BMI quartile among those aged ＜45 years than in those aged ≥ 45 years. Furthermore, the increase in nocturnal systolic blood pressure was higher in the highest TyG-BMI quartile groups among female patients than in male patients.