While total cholesterol and triglyceride levels have decreased in younger U.S. birth cohorts, fasting glucose levels have risen, with body mass index explaining only part of this trend in cardiometabolic health, according to a recent study.
In the serial cross-sectional analysis, researchers explored trends in total cholesterol, fasting triglyceride, and fasting glucose levels across U.S. birth cohorts born between 1920 and 1999. The study analyzed data from nine 2-year National Health and Nutrition Examination Survey cycles from 1999 to 2016, plus a pre-COVID-19 pandemic cycle from 2017 to March 2020, to assess how cardiometabolic health has evolved across generations and the potential role of body mass index (BMI) in mediating these trends.
Published in JAMA Network Open, the study included 52,006 participants, weighted to represent 264,664,915 U.S. adults, with a weighted median age of 46 years. Of these participants, 50.6% were women. Researchers found that total cholesterol and fasting triglyceride levels significantly decreased in more recent birth cohorts. Specifically, participants in more recent birth cohorts had a mean decrease of 7.1 mg/dL (95% confidence interval [CI], −8.2 to −6.1) in total cholesterol and 13.1 mg/dL (95% CI, −15.1 to −11.1) in fasting triglycerides compared to those in older cohorts. Fasting glucose levels increased by 2.7 mg/dL (95% CI, 2.3 to 3.1) per decade in younger cohorts. Additionally, BMI increased by 0.7 (95% CI, 0.6 to 0.9) at the 50th percentile per decade of birth years.
The study utilized quantile regression models to analyze changes in lipid and glucose levels, accounting for age, sex, and race. The researchers found that while BMI played a mediating role in these trends, particularly in fasting glucose levels, up to 80% of the association between birth cohort and cardiometabolic outcomes was not mediated through BMI. Causal mediation analysis further indicated that BMI contributed to the deceleration of favorable trends in total cholesterol and triglycerides and the acceleration of adverse trends in glucose. Supplementary analysis showed that statin use contributed significantly to the decreasing trends in lipid outcomes over the years.
These findings highlight the need for public health interventions targeting antecedent health behaviors to address rising obesity rates and improve cardiometabolic health across generations. While improvements in cholesterol and triglyceride levels have slowed, the increase in glucose levels highlights a critical area for intervention. The study provides insight into how generational shifts in lifestyle factors may influence long-term health outcomes.
The researchers noted several limitations, including the inability to assess individual-level changes over time due to the cross-sectional nature of the analysis, and that the causal mediation program used could not incorporate sampling weights, limiting the generalizability of the mediation results to the U.S. population.
Full disclosures can be found in the published study.
