Dairy Intake in Relation to Prediabetes and Continuous Glycemic Outcomes: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies.

Background: Modest inverse associations have been found between dairy intake, particularly yogurt, and type 2 diabetes risk. Investigating associations of dairy intake with early onset of type 2 diabetes offers opportunities for effective prevention of this condition.

Objectives: This study aims to investigate the relationships between the intake of different dairy types, prediabetes risk, and continuous glycemic outcomes.

Methods: Systematic literature searches across multiple databases were performed of studies published up to September 2023. Included were prospective cohort studies in healthy adults that examined the association between dairy intake and prediabetes risk according to diagnostic criteria, or continuous glycemic markers. A dose-response random-effects meta-analysis was used to derive incremental relative risks (RRs) for associations of total dairy, fermented dairy, milk, yogurt, cheese (all total, high-fat, and low-fat), cream, and ice cream with prediabetes risk adjusted for sociodemographic, health and cardiometabolic risk factors, and dietary characteristics.

Results: The meta-analyses encompassed 6653 prediabetes cases among 95,844 individuals (age range 45.5-65.5 y) including 6 articles describing 9 cohorts. A quadratic inverse association was observed for total dairy intake and prediabetes risk, with the lowest risk at 3.4 servings/d (RR: 0.75; 95% confidence interval: 0.60, 0.93; = 18%). Similarly, total, and high-fat cheese exhibited nonlinear inverse associations with prediabetes risk, showing the lowest risk at 2.1 servings/d (0.86; 0.78, 0.94; = 0%, and 0.90; 0.81, 0.99; = 12%), but a higher risk at intakes exceeding 4 servings/d. Ice cream intake was linearly associated with prediabetes risk (0.85; 0.73, 0.99; = 0% at the highest median intake of 0.23 servings/d). Other dairy types showed no statistically significant associations. The systematic review on dairy intake and glycemic outcomes showed considerable variabilities in design and results.

Conclusions: The findings suggest an inverse association between moderate dairy and cheese intake in preventing prediabetes. The potential for reverse causation and residual confounding highlights the need for studies with comprehensive repeated measurements.

Trial Registration Number: PROSPERO 2023 CRD42023431251.