# Association between blood urea nitrogen and the prevalence of Hashimoto's thyroiditis in adults with type 2 diabetes mellitus: a cross-sectional study

## TL;DR

Higher blood urea nitrogen levels are linked to a greater chance of Hashimoto's thyroiditis in adults with type 2 diabetes.

## Contribution

This study identifies a novel association between BUN and Hashimoto's thyroiditis in T2DM patients.

## Key findings

- Each 1 mmol/L increase in BUN was linked to a 7% higher chance of Hashimoto's thyroiditis.
- A nonlinear relationship was found with a significant increase in HT risk at lower BUN levels.
- The association remained consistent across various subgroups of patients.

## Abstract

Blood urea nitrogen (BUN), a known marker of renal function and protein catabolic status, is essential for inflammatory and metabolic dysregulation. There is currently little information available on the connection between BUN and Hashimoto's thyroiditis (HT) in individuals with type 2 diabetes mellitus (T2DM). The purpose of this study was to look into the relationship between HT and BUN in T2DM patients.

Two thousand fifty four adult T2DM patients from two hospitals were included in this cross-sectional analysis of data from the National Metabolic Management Center (MMC) cohort. The independent relationship between BUN and HT was evaluated using multivariable logistic regression models. Restricted cubic spline (RCS) regression was utilized to examine potential nonlinear correlations. The consistency of correlations across strata of sex, age, body mass index (BMI), and study center was assessed by subgroup analysis.

HT was present in 20.2% of cases (414/2054). Each 1 mmol/L rise in BUN was linked to a 7% greater chance of HT after adjusting for age, sex, education, duration of diabetes, BMI, HbA1c, smoking, drinking, hypertension, and hyperlipidemia (OR = 1.07, 95% CI: 1.01–1.13, P = 0.027). BUN and HT were shown to have a nonlinear relationship with an inflection point at 5.299 mmol/L. A 52.1% increase in prevalence of HT was linked to every 1 mmol/L increase when BUN was ≤5.299 mmol/L (OR = 1.521, 95% CI: 1.196–1.934, P < 0.001). All subgroups had consistent positive connections, according to subgroup analysis (all interaction P > 0.05).

Higher levels of BUN, particularly within a lower-to-moderate range, are independently associated with an increased prevalence of HT in patients with T2DM. These results imply that BUN, a commonly accessible metric, may be useful in identifying T2DM patients who are more likely to have concurrent autoimmune thyroiditis.