# Within- and Between-Individual Variations in Protein, Sodium, Potassium, and Phosphorus Intake Estimated from Urinary Biomarkers and Dietary Records in Individuals with Type 2 Diabetes Mellitus

## TL;DR

This study compares urine and dietary records to assess nutrient intake variations in people with type 2 diabetes, finding urine collection to be more consistent for some nutrients.

## Contribution

The study provides sex-specific insights into the reliability of urine-based vs. dietary record methods for estimating nutrient intake in individuals with type 2 diabetes.

## Key findings

- 24 h urine collection showed smaller within-individual variation than dietary records for protein and phosphorus in both sexes.
- Sodium and potassium variations showed sex-specific differences, with urine collection being less variable in males but more variable in females.
- Dietary records underestimated sodium intake compared to urine-based estimates.

## Abstract

Background/Aim: Appropriate dietary assessment plays a crucial role in individualized nutritional therapy for individuals with type 2 diabetes mellitus (T2DM). Daily dietary variations must be considered in the estimation of usual dietary intake, and such data are limited in individuals with T2DM. This study aimed to evaluate within- and between-individual variations in protein, sodium, potassium, and phosphorus intakes estimated from 24 h urine collection (24 h UC) and semi-weighted dietary records (DRs) in Japanese individuals with T2DM. Methods: This study included 39 Japanese individuals (26 males, 13 females; mean age 64.6 years) with T2DM who attended two hospitals. Protein, sodium, potassium, and phosphorus intakes were estimated using 2-day 24 h UC and 3-day DRs and within- and between-individual variations were calculated using a one-way analysis of variance. Results: The mean protein, potassium, and phosphorus intakes did not significantly differ between 24 h UC and DRs. However, sodium intake was lower when estimated by DRs than by 24 h UC. The coefficients of within-individual variation (CVw) differed between 24 h UC and DRs. For protein and phosphorus, the CVw values were smaller by 12.5% and 8.0% in males and 2.3% and 3.0% in females, respectively, for 24 h UC than DRs. For sodium and potassium, the CVw values were smaller by 7.0% and 4.8% in males, but larger by 5.0% and 3.3% in females, respectively, for 24 h UC than DRs. Conclusions: Our findings demonstrated that 24 h UC showed smaller within-individual variations than DRs for protein and phosphorus in both sexes, with sex-specific differences for sodium and potassium.