The Relationship Between a Low-Carbohydrate Diet and the Prevalence of Diabetic Kidney Disease in Patients With Type 2 Diabetes: A Cross-Sectional Study.

Diabetic kidney disease (DKD) affects over 40% of patients with type 2 diabetes mellitus (T2DM), yet effective preventive strategies remain limited. Although low-carbohydrate dietary (LCD) shows promise in glycemic control, their association with DKD prevalence is poorly understood. This study aimed to investigate the relationship between LCD adherence and DKD risk in a nationally representative T2DM population. 4558 adults with T2DM from the U.S. National Health and Nutrition Examination Survey were included (NHANES, 2009-2018). LCD adherence was quantified using the validated Low-Carbohydrate Diet Score (LCDS, range 0-30), calculated from two 24-h dietary recalls. DKD was defined as albumin-to-creatinine ratio ≥ 30 mg/g or estimated glomerular filtration rate < 60 mL/min/1.73 m2. Restricted cubic splines (RCS) modeled non-linear associations, and weighted multivariable logistic regression analysis was conducted to explore the relationship between LCDS and the prevalence of DKD in T2DM patients, along with stratified analyses to assess the interaction of the results. The mean LCDS was 12.058, with higher scores in males, high-income individuals, and insulin users (all p < 0.05). RCS revealed a linear inverse association between LCDS and DKD prevalence (p for nonlinearity = 0.490). In fully adjusted models, participants in the highest LCDS tertile (T3 vs. T1) had 21.5% lower DKD prevalence (OR = 0.785; 95% CI, 0.628-0.982; p = 0.034). Stratified analyses demonstrated no significant interaction effects between LCDS and covariates including age, sex, body mass index, or HbA1c (all p for interaction > 0.05). These findings highlight that higher LCDS was inversely associated with DKD prevalence in patients with T2DM. Future prospective studies should validate causality and optimize LCD protocols for renal protection.