Association between plasma homocysteine levels and pancreatic islet beta-cell function in the patients with type 2 diabetes mellitus: a cross-sectional study from China.

Abstract

This study sought to investigate the association between plasma homocysteine (HCY) levels and pancreatic islet beta-cell function in type 2 diabetes mellitus (T2DM) patients. 430 hospitalized T2DM patients were enrolled in this cross-sectional study from December 2013 to December 2016. All participants were requested to complete a detailed questionnaire and undergo anthropometric measurements. Blood samples were collected from all participants. A 75-g oral glucose tolerance test (OGTT) was performed to diagnose T2DM in each individual, and an insulin releasing test (IRT) was used to calculate selected parameters for glucose, insulin, and C-peptide. Linear correlation and multivariate regression analyses were performed to assess the association between serum HCY concentration and these parameters. Patients were divided into the following subgroups based on quartiles of serum HCY levels: Group Q1: <17.03 µmol/L; Group Q2: 17.03-19.50 µmol/L; Group Q3: 19.5-24.7 µmol/L; and Group Q4: >24.7 µmol/L. The levels of fasting blood glucose (FBG), 2 h postprandial blood glucose (2hPBG), glycated hemoglobin A1c (HbA1c), fasting C-peptide and fasting insulin increased significantly as HCY levels increased (P<0.05). The area under the curves (AUCs) of serum glucose and insulin in IRT increased significantly and that of serum C-peptide decreased as HCY levels increased (P<0.05). The levels of Homeostasis Model Assessment-β (HOMA-β), Modified Beta-cell function Index (MBCI), Disposal Index (DI), C-peptide immunoreactivity (CPR), Insulinogenic Index 30 (IGI 30), and Secretory Units of Islets in Transplantation (SUIT) decreased as HCY levels increased. An inverse linear correlation was found between HOMA-β, MBCI, DI, CPR, IGI 30, SUIT 0 h, and HCY plasma concentration (R2, 0.539, 0.569, 0.500, 0.676, 0.579, and 0.588, respectively; P<0.001), and this association was independent of many confounders, such as age, gender, body mass index, glucose and insulin levels, and HbA1c. Serum HCY levels were inversely related to the parameters for pancreatic islet beta-cell function. Thus, the insulin releasing function of beta cells in the pancreas can be well elucidated by plasma HCY concentration.