Postdiagnosis 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

Abstract

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: We aimed to prospectively examine associations of 11 predefined or empirically developed dietary patterns with all-cause and cause-specific mortality [e.g., cardiovascular disease (CVD) and cancer] among United States individuals with T2D. Methods: We included 7795 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 4 y. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Results: Over 24 y of follow-up, 3509 deaths were confirmed, including 1079 deaths from CVD and 649 deaths 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 prediagnosis to postdiagnosis (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. In addition, the reversed empirical dietary index for hyperinsulinemia was specifically associated with lower cancer-related 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.