25-Hydroxyvitamin D Is Associated with Islet Homeostasis in Type-2 Diabetic Patients with Abdominal Obesity

Qing Li; Wen Zhang; Bing Han; Yu-Ying Wang; Heng Wan; Min Zhang; Ning-Jian Wang; Ying-Li Lu

doi:10.1007/s11596-023-2780-z

25-Hydroxyvitamin D Is Associated with Islet Homeostasis in Type-2 Diabetic Patients with Abdominal Obesity

Curr Med Sci. 2023 Oct;43(5):919-926. doi: 10.1007/s11596-023-2780-z. Epub 2023 Sep 12.

Authors

Qing Li^#¹, Wen Zhang^#¹, Bing Han¹, Yu-Ying Wang¹, Heng Wan¹, Min Zhang², Ning-Jian Wang³, Ying-Li Lu⁴

Affiliations

¹ Institute and Department of Endocrinology and Metabolism, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200011, China.
² Institute and Department of Endocrinology and Metabolism, Qingpu Branch of Zhongshan Hospital Affiliated to Fudan University, Shanghai, 201700, China. 18116016187@163.com.
³ Institute and Department of Endocrinology and Metabolism, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200011, China. wnj486@126.com.
⁴ Institute and Department of Endocrinology and Metabolism, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200011, China. luyingli2008@126.com.

^# Contributed equally.

PMID: 37697161
DOI: 10.1007/s11596-023-2780-z

Abstract

Objective: Islet α cells input is essential for insulin secretion from β cells. The present study aims to investigate the association between 25-hydroxyvitamin D [25(OH)D] and islet function homeostasis in type-2 diabetes (T2D) patients.

Methods: A total of 4670 T2D patients from seven communities in Shanghai, China were enrolled. The anthropometric indices, biochemical parameters, serum 25(OH)D, and islet function [including C-peptide (C-p) and glucagon] were measured.

Results: The fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), glucagon, and C-p levels exhibited a significantly decreasing trend in T2D patients as the 25(OH)D levels increased. Next, the population was divided into two groups: abdominal obesity and non-abdominal obesity groups. After adjustment, the 25(OH)D level was found to be associated with HbA1c, glucagon, and homeostasis model assessment of β (HOMA-β) in the non-abdominal obesity group. There was a significant relationship between 25(OH)D and HbA1c, glucagon, HOMA-IR, baseline insulin or C-p in the abdominal obesity group. In the abdominal obesity group, the ordinary least squares (OLS) regression and quantile regression revealed that 25(OH) D was obviously associated with glucagon and fasting C-p levels. In the abdominal obesity group, the moderate analysis revealed a significant interaction effect of 25(OH)D and glucagon on C-p (P=0.0124). Furthermore, the conditional indirect effect of 25(OH)D on the glucagon/C-p ratio was significantly lower at 1 standard deviation (SD) below the mean (P=0.0002), and lower at the mean of the course of diabetes (P=0.0007).

Conclusion: 25(OH)D was found to be negatively correlated to glucagon and C-p in T2D patients with abdominal obesity. The 25(OH)D influenced C-p in part by influencing glucagon. The effect of 25(OH)D on the glucagon/C-p ratio in T2D patients with abdominal obesity, in terms of islet homeostasis, is influenced by the course of diabetes.

Keywords: 25-hydroxyvitamin D; C-peptide; glucagon; islet α cells; islet β cells; type-2 diabetes.