Generated Summary
This systematic review and meta-analysis investigated the relationship between dietary factors and all-cause mortality in individuals with type 2 diabetes. The study adhered to the PRISMA 2020 statement and included prospective observational studies published in peer-reviewed journals. The search encompassed PubMed and Web of Science up to June 2022. The review considered various dietary factors, including dietary patterns, food groups, foods, macro- and micronutrients, and secondary plant compounds. The risk of bias was assessed using the Risk Of Bias In Non-randomised Studies-of Interventions (ROBINS-I) tool, and the certainty of evidence was evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach.
Key Findings & Statistics
- A total of 107 studies were included in the systematic review, with 72 studies included in 45 meta-analyses.
- Higher intakes of fish (6 studies) were associated with a lower risk of all-cause mortality (SRR per serving/week: 0.95; 95% CI 0.92, 0.99; moderate certainty).
- Whole grain consumption (2 studies) showed an inverse association with all-cause mortality (SRR per 20 g/day: 0.84; 95% CI 0.71, 0.99; moderate certainty).
- Fiber intake (3 studies) was inversely associated with mortality (SRR per 5 g/day: 0.86; 95% CI 0.81, 0.91; moderate certainty).
- n-3 PUFA intake (2 studies) was inversely associated with all-cause mortality (SRR per 0.1 g/day: 0.87; 95% CI 0.82, 0.92; moderate certainty).
- Vegetable consumption (2 studies) showed an inverse association, (SRR per 100 g/day: 0.88; 95% CI 0.82, 0.94; low certainty).
- Plant protein intake (3 studies) was inversely associated with all-cause mortality (SRR per 10 g/day: 0.91; 95% CI 0.87, 0.96; low certainty).
- Egg consumption (7 studies) was positively associated with all-cause mortality (SRR per 10 g/day: 1.05; 95% CI 1.03, 1.08; low certainty).
- Cholesterol intake (2 studies) was positively associated with all-cause mortality (SRR per 300 mg/day: 1.19; 95% CI 1.13, 1.26; low certainty).
- The Mediterranean diet (3 studies) showed an inverse association with mortality (SRR 0.73; 95% CI 0.58, 0.91; very low certainty).
- Alternate Healthy Eating Index (2 studies) showed an inverse association with mortality (SRR 0.60; 95% CI 0.48, 0.75; very low certainty).
- Higher intake of saturated fatty acids pointed to an increased relative risk (low certainty).
- The substitution of 2% energy from carbohydrates with plant protein was inversely associated with all-cause mortality (SRR 0.76; 95% CI 0.66, 0.87).
- The substitution of 2% energy from carbohydrates with saturated fatty acids positively associated with all-cause mortality (SRR 1.10; 95% CI 1.04, 1.16).
- No associations were found for caffeine consumption, serum folate and alcohol consumption.
Other Important Findings
- The study identified that the higher intake of fish, whole grain, fiber, and n-3 polyunsaturated fatty acids were inversely associated with all-cause mortality in individuals with type 2 diabetes (moderate certainty of evidence).
- Higher intakes of vegetables and plant protein may be inversely associated with all-cause mortality (low certainty).
- Higher intakes of eggs and cholesterol may be positively associated with all-cause mortality (low certainty).
- The study found no association for other dietary factors, with the evidence being very uncertain.
- The certainty of evidence for the associations between dietary patterns and all-cause mortality was very low.
- A meta-analysis based on 22 cohort studies, a dietary increment of 200 g of vegetables per day was associated with a 13% decreased risk of all-cause mortality in the general population (86).
Limitations Noted in the Document
- The main limitation was the serious risk of bias in most studies, primarily due to uncontrolled confounding and selection of participants.
- Most studies were at a serious risk of bias, mainly due to uncontrolled confounding and selection of participants.
- Dietary intake assessment relied on self-reports, which may lead to misclassification.
- Changes in dietary behavior during follow-up were not always considered.
- Many meta-analyses had a small number of studies, leading to imprecisely estimated effect estimates.
- Subgroup analyses and publication bias were limited.
- The study did not include stratified analyses for different subgroups of individuals.
Conclusion
The study concludes that higher intakes of fish, whole grains, fiber, and n-3 PUFA are inversely associated with all-cause mortality in individuals with type 2 diabetes. The authors emphasize that these findings suggest the need for robust and comprehensive evidence on the role of dietary factors in managing diabetes and its progression. The authors emphasize that these findings suggest the need for robust and comprehensive evidence on the role of dietary factors in managing diabetes and its progression. The study highlights the importance of dietary factors in the context of type 2 diabetes, emphasizing that the evidence base for specific dietary recommendations for individuals with type 2 diabetes is currently limited. The study reinforces the need for more research that addresses these limitations, particularly by accounting for crucial confounders like diabetes duration and treatment, and by employing standardized, validated dietary assessment methods. The authors underscore the need for future research to address the limitations identified in the meta-analysis. They suggest that future studies should focus on factors such as diabetes duration, treatment, socioeconomic status, and total energy intake to strengthen the evidence. The authors also recommend the use of validated dietary assessment methods and the consideration of dietary behavior changes during follow-up to enhance the reliability and certainty of evidence. The study advocates for further research to refine dietary guidelines and improve outcomes for individuals with type 2 diabetes. In summary, the study’s findings highlight the potential of dietary interventions to improve outcomes in individuals with type 2 diabetes. The review emphasizes the need for more research to enhance the understanding of the links between diet and mortality in this population, ultimately improving the evidence base for dietary guidelines.