Impact of a low‐carbohydrate diet on cardiometabolic parameters in individuals with and without diabetes: An 8‐year longitudinal study within the ELSA‐Brasil cohort

Background Low‐carbohydrate diets (LCDs) are widely adopted for metabolic management, but their long‐term cardiometabolic effects in diverse populations remain unclear. We aimed to evaluate the association between self‐selected moderate LCD adherence and cardiometabolic parameters in individuals with and without diabetes. Methods This prospective cohort study included 9658 participants from the Brazilian Longitudinal Study of Adult Health (ELSA‐Brasil; baseline: 2008–2010; follow‐up: 2017–2019). LCD adherence (carbohydrate <45% of total energy) was assessed through validated food frequency questionnaires. Quantile regression models, adjusted for sociodemographic, lifestyle, and clinical factors, were used to analyze changes in body mass index (BMI), blood pressure, insulin, and homeostatic model assessment for insulin resistance (HOMA‐IR) and beta cell function (HOMA‐B). Results Among individuals without diabetes, those who followed an LCD only at the follow‐up showed decreased insulin levels (β = −0.33 [95% CI, −0.6 to −0.1] μIU/ml), HOMA‐IR (−0.11 [−0.2 to −0.1] μIU/ml), and HOMA‐B (−4.95 [−7.2 to −2.1] μIU/ml) alongside modest BMI increases (0.16 [0.1–0.3]). Consistent LCD adherents (at both time points) showed a decrease in HOMA‐B (−3.21 [−6.4 to −0.1] μIU/ml) and an increase in BMI (0.29 [0.2–0.4]). In individuals with diabetes, LCD adherence led to reduced HOMA‐IR (−1.25 [−2.2 to −0.3] μIU/ml) and insulin levels (−3.61 [−6.0 to −1.2] μIU/ml). Conclusion Moderate LCD adherence improved insulin sensitivity and reduced pancreatic demand in individuals without diabetes. Despite slight BMI increases, LCD may be a feasible dietary strategy for metabolic risk management in middle‐aged and older adults. Personalized nutrition approaches are recommended to optimize outcomes.