Post-Diagnosis Healthy Dietary Patterns in Relation to All-Cause and Cause-Specific Mortality and Life Expectancy among Adults with Type 2 Diabetes: Evidence from Cohort Studies.
BACKGROUND Type 2 diabetes (T2D) is associated with an increased risk of premature death. Diet may influence long-term health outcomes among individuals with T2D, but prospective evidence on dietary patterns and mortality remains limited. OBJECTIVES To prospectively examine associations of eleven pre-defined or empirically-developed dietary patterns with all-cause and cause-specific mortality (e.g., cardiovascular disease [CVD] and cancer) among U.S. individuals with T2D. METHODS We included 7,795 participants with incident T2D in the Nurses' Health Study (1984-2016) and Health Professionals Follow-Up Study (1986-2020), who were free of CVD and cancer at diagnosis. Diet was assessed using a validated food frequency questionnaire and updated every four years. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs. RESULTS Over 24 years of follow-up, 3,509 deaths were confirmed, including 1,079 from CVD and 649 from cancer. Adherence to healthy dietary patterns after diagnosis (comparing the 90th with the 10th percentile of dietary pattern scores) was consistently associated with lower all-cause mortality, with multivariable-adjusted HRs ranging from 0.78 (95% CI: 0.71, 0.85) for the Planetary Health Diet to 0.92 (95% CI: 0.84, 1.01) for the Dietary Approaches to Stop Hypertension. Furthermore, greater improvements in dietary pattern adherence from pre- to post-diagnosis (comparing the 90th with the 10th percentile of change scores) were also associated with lower all-cause mortality, with HRs (95% CI) ranging from 0.63 (0.58, 0.70) to 0.92 (0.85, 1.01). A similar pattern of inverse associations with CVD mortality was also observed for these dietary scores. Additionally, the reversed Empirical Dietary Index for Hyperinsulinemia was specifically associated with lower cancer mortality. CONCLUSIONS Adherence to healthy dietary patterns is universally associated with better survival in individuals with T2D. These findings suggest the importance of consuming high-quality diets in the prevention of premature deaths among individuals with T2D.