Red Meat Consumption and Type 2 Diabetes

Type 2 diabetes (T2D) is a growing global public health concern. Observational studies have suggested a link between red meat intake and T2D risk, but short-term randomized controlled trials (RCTs) have not provided definitive evidence. This study aims to investigate the association between red meat consumption and T2D incidence in three large cohorts over an extended 30-year period, considering methodological advancements and potential confounders.

Methods:

The study includes participants from the Nurses' Health Study (NHS), Nurses' Health Study II (NHS II), and Health Professionals Follow-up Study (HPFS). Data were collected through biennial questionnaires, including dietary information assessed every 2 to 4 years. The analysis involved over 84,000 females from the NHS, 90,000 females from the NHS II, and 42,000 males from the HPFS.

Exposure and Covariates:

Red meat intake was assessed using food frequency questionnaires, with calibration studies improving accuracy. Covariates included demographics, lifestyle factors, and health-related variables. The analysis used Cox proportional hazards models, adjusting for multiple factors, and explored potential interactions.

Diabetes Incidence:

Incident T2D cases were reported through biennial questionnaires, confirmed using established criteria. Person-years of follow-up were calculated, and Cox models estimated hazard ratios for associations between total red meat, processed red meat, and unprocessed red meat with T2D incidence.

Statistical Analysis:

Analyses involved categorizing red meat intake, examining linear trends, and assessing nonlinear relationships using restricted cubic splines. Sensitivity analyses considered BMI adjustment, latency periods, and reverse causation. Subgroup analyses explored interactions with variables such as physical activity, BMI, hypertension, smoking status, and race/ethnicity.

Results:

Over 5.4 million person-years, 11,369 T2D cases (NHS), 7,624 cases (NHS II), and 3,768 cases (HPFS) were documented. Higher red meat intake was associated with higher BMI, energy intake, and lower physical activity. The analysis considered latency periods and examined the impact of reverse causation.

Conclusion:

This comprehensive study provides insights into the long-term association between red meat consumption and T2D risk. The findings contribute to the ongoing discussion on dietary recommendations for preventing T2D, highlighting the importance of considering various factors and utilizing robust study designs.