Retrospective Study
Copyright ©The Author(s) 2025. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Diabetes. Jul 15, 2025; 16(7): 107019
Published online Jul 15, 2025. doi: 10.4239/wjd.v16.i7.107019
First metatarsophalangeal joint synovial hypertrophy associated with vitamin D status in type 2 diabetes mellitus: An ultrasound-graded study
Qing-Shan Li, Xiao-Hui Xiao, Yu-Ying Cai, Xiao-Peng Xiao, Ping-Xiang Hu, Hong Li
Qing-Shan Li, Yu-Ying Cai, Xiao-Peng Xiao, Ping-Xiang Hu, Hong Li, Department of Ultrasound, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine (Shenzhen Traditional Chinese Medicine Hospital), Shenzhen 518000, Guangdong Province, China
Xiao-Hui Xiao, Department of Endocrinology, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine (Shenzhen Traditional Chinese Medicine Hospital), Shenzhen 518000, Guangdong Province, China
Co-corresponding authors: Ping-Xiang Hu and Hong Li.
Author contributions: Li QS contributed to image acquisition and analysis, writing original draft; Xiao XH contributed to collect clinical and laboratory data; Cai YY contributed to data curation, formal analysis; Xiao XP contributed to image quality supervision and image analysis; Hu PX contributed to project administration; Li H contributed to writing review and editing; All authors participated in the discussion of the manuscript and agreed on the content and publication of the final manuscript.
Institutional review board statement: This study was approved by the Shenzhen Traditional Chinese Medicine Hospital Ethics Committee (No. K2023/098/02) and adhered to the principles outlined in the Declaration of Helsinki.
Informed consent statement: All participants provided written informed consent.
Conflict-of-interest statement: The authors declare that they have no conflict of interest.
Data sharing statement: The datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request.
Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Hong Li, MD, Doctor, Professor, Department of Ultrasound, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine (Shenzhen Traditional Chinese Medicine Hospital), No. 1 Fuhua Road, Futian District, Shenzhen 518000, Guangdong Province, China. lihong_echo@163.com
Received: March 17, 2025
Revised: April 26, 2025
Accepted: June 19, 2025
Published online: July 15, 2025
Processing time: 124 Days and 6.9 Hours
Abstract
BACKGROUND

The existing semi-quantitative ultrasound grading system inadequately evaluates synovial hypertrophy at the dorsal recess of the first metatarsophalangeal joint (MTPJ). Vitamin D deficiency is prevalent in type 2 diabetes mellitus (T2DM) and may influence joint inflammation. This study hypothesizes that serum 25-hydroxyvitamin D [25(OH)D] levels are inversely associated with synovial hypertrophy severity of the first MTPJ in patients with T2DM.

AIM

To refine ultrasound grading for the first MTPJ synovial hypertrophy and investigate its association with vitamin D in T2DM.

METHODS

This cross-sectional study included 56 patients (112 MTPJs) with T2DM from Shenzhen Traditional Chinese Medicine Hospital. Synovial hypertrophy was evaluated using a refined semi-quantitative ultrasound grading system focusing on the dorsal recess overlying the metatarsal bone. Serum 25(OH)D levels were measured. Logistic regression and threshold analyses assessed associations between vitamin D status and hypertrophy severity.

RESULTS

Of 112 joints assessed, 98 exhibited synovial hypertrophy (grade 1: 40; grade 2: 50; grade 3: 8). The refined grading system demonstrated strong intra- and inter-observer reliability (intraclass correlation coefficients = 0.79 and 0.73, respectively). Lower serum 25(OH)D (< 24.3 ng/mL) was independently associated with moderate-to-severe hypertrophy [odds ratio (OR) = 0.83; P = 0.0163]. Vitamin D deficiency significantly increased the likelihood of moderate-to-severe hypertrophy compared with non-deficiency (OR = 3.86; P = 0.0422). Threshold analysis identified 23.8 ng/mL as a critical serum 25(OH)D level, below which each increment reduced moderate-to-severe hypertrophy risk by 21% (OR = 0.79; P = 0.0078).

CONCLUSION

The refined ultrasound grading system demonstrated strong reliability. Serum 25(OH)D may serve as a protective factor against the severity of synovial hypertrophy in T2DM patients with lower 25(OH)D levels.

Keywords: Vitamin D; Synovial hypertrophy; Type 2 diabetes mellitus; Metatarsophalangeal joint; Serum 25-hydroxyvitamin D

Core Tip: This study refines a semi-quantitative ultrasound grading system for first metatarsophalangeal joint synovial hypertrophy by introducing a novel subtype that specifically classifies cases of dorsal recess overlying the metatarsal bone, demonstrating high reliability (intra-observer intraclass correlation coefficient = 0.79; inter-observer intraclass correlation coefficient = 0.73). We identified a significant inverse, non-linear correlation between serum 25-hydroxyvitamin D levels and synovial hypertrophy severity, with a threshold effect at 23.8 ng/mL. These findings suggest that vitamin D deficiency may contribute to synovial inflammation in type 2 diabetes mellitus patients and that targeted screening and supplementation could help mitigate joint complications.