Low-Carbohydrate Diets of Varying Macronutrient Quality and Risk of Type 2 Diabetes in Three U.S. Prospective Cohort Studies
Authors' conclusion
LCDs may not be beneficial for primary prevention of T2D unless they prioritize plant-based protein, healthy fats, and high-quality carbohydrates.
Study context
- Population
- U.S. adults from Nurses' Health Study (NHS) (1984–2018), NHSII (1991–2019) and Health Professionals Follow-up Study (1986–2018), free of T2D, CVD and cancer at baseline; followed over 30 yearsU.S
- Participants
- 199,006 adults
- Exposure
- Highest vs lowest quintile of five low-carbohydrate diet (LCD) scores differentiated by macronutrient quality
- Outcome
- Incident T2D
Methodological detailsthree U.S. prospective cohorts (NHS, NHSII, HPFS), diet assessed every 2-4 years by validated food frequency questionnaires
- Three U.S. prospective cohorts (NHS, NHSII, HPFS)
- Diet assessed every 2-4 years by validated food frequency questionnaires
Main finding
As reported in the abstract
Incident T2D by LCD score (highest vs lowest quintile)
Highest quintile vs Lowest quintileHazard ratio (95% CI)P value
Overall LCD
1.31(1.25–1.37)
P < 0.001for trendAnimal-based LCD
1.39(1.32–1.45)
P < 0.001for trendUnhealthy LCD
1.44(1.37–1.51)
P < 0.001for trendVegetable-based LCD; 6% lower T2D risk
0.94(0.90–0.98)
P = 0.004for trendHealthy LCD; 16% lower T2D risk
0.84(0.81–0.88)
P < 0.001for trend- T2D cases during 4,987,761 person-years of follow-up
- 20,452
Observational data: associations, not effects.
Further findings
Effect modification and mediation
- Associations for overall, animal-based and unhealthy low-carbohydrate diets (LCDs) stronger with lower baseline BMI and partially mediated by weight change
Original publication
Low-Carbohydrate Diets of Varying Macronutrient Quality and Risk of Type 2 Diabetes in Three U.S. Prospective Cohort Studies. Diabetes Care. Published 30 September 2025. doi:10.
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